Levothyroxine sodium
Generic name: levothyroxine sodium · Brand names: Levo-T, Levoxyl, Synthroid, Unithroid, Tirosint (capsule, separate product), Levothroid (no longer on the market)
Quick facts
Drug class
Levothyroxine is L-thyroxine (T4), a thyroid hormone. It replaces thyroid hormone the body normally makes.
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
Highlights, Indications and Usage
Verbatim
Levothyroxine sodium tablets are a L-thyroxine (T4) indicated in adult and pediatric patients, including neonates, for:
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
Why is this medication prescribed?
Verbatim
Levothyroxine is in a class of medications called hormones. It works by replacing thyroid hormone that is normally produced by the body.
Rx or otc
Rx
Forms and strengths
- Tablets, USP: 25, 50, 75, 88, 100, 112, 125, 137, 150, 175 and 200 mcg (NorthStar label Section 3). Other levothyroxine products (capsule, solution, injection) are separate and not covered. Standard tablet only.
Generic available
Value
Yes. NorthStar tablets are ANDA211417 (manufactured by Macleods); other ANDA and NDA authorized generic tablet labels are on DailyMed.
Source
DailyMed NorthStar label Marketing Information; DailyMed list
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Common use one line
Replaces thyroid hormone in hypothyroidism; add-on to surgery and radioiodine for thyroid cancer.
What it is used for
Levothyroxine is used in adults and children, including newborns, as replacement therapy in primary, secondary and tertiary hypothyroidism (congenital or acquired). It is also used as an adjunct to surgery and radioiodine therapy for thyrotropin-dependent well-differentiated thyroid cancer. It is not indicated to suppress benign thyroid nodules or nontoxic diffuse goiter in iodine-sufficient patients, or to treat hypothyroidism during the recovery phase of subacute thyroiditis. It is the generic of Synthroid and other brands.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
1 INDICATIONS AND USAGE
Verbatim
Hypothyroidism
Levothyroxine sodium tablets are indicated in adult and pediatric patients, including neonates, as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.
Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression
Levothyroxine sodium tablets are indicated in adult and pediatric patients, including neonates, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.
Limitations of Use
Levothyroxine sodium tablets are not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients as there are no clinical benefits and overtreatment with levothyroxine sodium tablets may induce hyperthyroidism [see Warnings and Precautions (5.1)].
Levothyroxine sodium tablets are not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.
Levothyroxine sodium tablets are indicated in adult and pediatric patients, including neonates, as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.
Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression
Levothyroxine sodium tablets are indicated in adult and pediatric patients, including neonates, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.
Limitations of Use
Levothyroxine sodium tablets are not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients as there are no clinical benefits and overtreatment with levothyroxine sodium tablets may induce hyperthyroidism [see Warnings and Precautions (5.1)].
Levothyroxine sodium tablets are not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
Why is this medication prescribed?
Verbatim
Levothyroxine is used to treat hypothyroidism (condition where the thyroid gland does not produce enough thyroid hormone). It is also used with surgery and radioactive iodine therapy to treat thyroid cancer.
How it works
Thyroid hormones act by controlling DNA transcription and protein synthesis. T3 and T4 enter the cell nucleus and bind to thyroid receptor proteins attached to DNA, which activates gene transcription. Most of the physiological action comes from T3, about 80% of which is made from T4 in peripheral tissues.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
12.1 Mechanism of Action
Verbatim
Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA. This hormone nuclear receptor complex activates gene transcription and synthesis of messenger RNA and cytoplasmic proteins.
The physiological actions of thyroid hormones are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues.
The physiological actions of thyroid hormones are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues.
Dosage: adults
Take it as a single daily dose on an empty stomach, one-half to one hour before breakfast, and at least 4 hours before or after drugs that interfere with absorption. For adults with hypothyroidism the full replacement dose is 1.6 mcg/kg/day, though some need a lower starting dose, with titration by 12.5 to 25 mcg every 4 to 6 weeks until euthyroid. Adults at risk for atrial fibrillation or with cardiac disease, and geriatric patients, start lower (less than 1.6 mcg/kg/day); the cardiac group titrates every 6 to 8 weeks. Peak effect may take 4 to 6 weeks. TSH is monitored 6 to 8 weeks after any dose change in primary hypothyroidism.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
2.1 Important Administration Instructions
Verbatim
Administer levothyroxine sodium tablets as a single daily dose, on an empty stomach, one-half to one hour before breakfast.
Administer levothyroxine sodium tablets at least 4 hours before or after drugs known to interfere with levothyroxine sodium absorption [see Drug Interactions (7.1)].
Administer levothyroxine sodium tablets at least 4 hours before or after drugs known to interfere with levothyroxine sodium absorption [see Drug Interactions (7.1)].
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
2.2 Important Considerations for Dosing
Verbatim
The peak therapeutic effect of a given dose of levothyroxine sodium tablets may not be attained for 4 to 6 weeks.
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
2.3 Table 1
Verbatim
Adults diagnosed with hypothyroidism: Full replacement dose is 1.6 mcg/kg/day. Some patients require a lower starting dose. Titrate dosage by 12.5 to 25 mcg increments every 4 to 6 weeks, as needed until the patient is euthyroid.
Adults at risk for atrial fibrillation or with underlying cardiac disease: Lower starting dose (less than 1.6 mcg/kg/day). Titrate dosage every 6 to 8 weeks, as needed until the patient is euthyroid.
Geriatric patients: Lower starting dose (less than 1.6 mcg/kg/day)
* Dosages greater than 200 mcg/day are seldom required. An inadequate response to daily dosages greater than 300 mcg/day is rare and may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors
Adults at risk for atrial fibrillation or with underlying cardiac disease: Lower starting dose (less than 1.6 mcg/kg/day). Titrate dosage every 6 to 8 weeks, as needed until the patient is euthyroid.
Geriatric patients: Lower starting dose (less than 1.6 mcg/kg/day)
* Dosages greater than 200 mcg/day are seldom required. An inadequate response to daily dosages greater than 300 mcg/day is rare and may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
2.4 Monitoring (Adults)
Verbatim
In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
How should this medicine be used?
Verbatim
It usually is taken once a day on an empty stomach, 30 minutes to 1 hour before breakfast.
Dosage: children
Pediatric starting doses are by weight and age: 0-3 months 10-15 mcg/kg/day, 3-6 months 8-10, 6-12 months 6-8, 1-5 years 5-6, 6-12 years 4-5, over 12 years with growth and puberty incomplete 2-3, and growth and puberty complete 1.6 mcg/kg/day. Titrate every 2 weeks as needed. Tablets can be crushed in 5 to 10 mL of water and given right away by spoon or dropper; do not give with soybean-based infant formula. Infants from birth to 3 months at risk for cardiac failure start lower, and infants should be closely monitored for the first 2 weeks.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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Section
2.1
Verbatim
Administer levothyroxine sodium tablets to pediatric patients who cannot swallow intact tablets by crushing the tablet, suspending the freshly crushed tablet in a small amount (5 to 10 mL) of water and immediately administering the suspension by spoon or dropper. Ensure the patient ingests the full amount of the suspension. Do not store the suspension. Do not administer in foods that decrease absorption of levothyroxine sodium, such as soybean-based infant formula [see Drug Interactions (7.9)].
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
2.3 Table 2 (starting daily dosage per kg body weight; 'Adjust dosage based on clinical response and laboratory parameters')
Verbatim
0-3 months 10-15 mcg/kg/day
3-6 months 8-10 mcg/kg/day
6-12 months 6-8 mcg/kg/day
1-5 years 5-6 mcg/kg/day
6-12 years 4-5 mcg/kg/day
Greater than 12 years but growth and puberty incomplete 2-3 mcg/kg/day
Growth and puberty complete 1.6 mcg/kg/day
3-6 months 8-10 mcg/kg/day
6-12 months 6-8 mcg/kg/day
1-5 years 5-6 mcg/kg/day
6-12 years 4-5 mcg/kg/day
Greater than 12 years but growth and puberty incomplete 2-3 mcg/kg/day
Growth and puberty complete 1.6 mcg/kg/day
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
2.3
Verbatim
Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid [see Dosage and Administration (2.2)].
Pediatric Patients from Birth to 3 Months of Age at Risk for Cardiac Failure
Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response.
Pediatric Patients at Risk for Hyperactivity
To minimize the risk of hyperactivity, start at one-fourth the recommended full replacement dosage, and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached.
Pediatric Patients from Birth to 3 Months of Age at Risk for Cardiac Failure
Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response.
Pediatric Patients at Risk for Hyperactivity
To minimize the risk of hyperactivity, start at one-fourth the recommended full replacement dosage, and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached.
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
8.4 Pediatric Use
Verbatim
Closely monitor infants during the first 2 weeks of levothyroxine sodium therapy for cardiac overload and arrhythmias.
Dosage adjustments
Drug interaction caps
Give levothyroxine at least 4 hours apart from phosphate binders, and at least 4 hours before bile acid sequestrants and ion exchange resins (or monitor TSH levels).
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
7.1 Table 5
Verbatim
Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum): Phosphate binders may bind to levothyroxine. Administer levothyroxine sodium tablets at least 4 hours apart from these agents.
Bile Acid Sequestrants (e.g., colesevelam, cholestyramine, colestipol), Ion Exchange Resins (e.g., Kayexalate): Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer levothyroxine sodium tablets at least 4 hours prior to these drugs or monitor TSH levels.
Bile Acid Sequestrants (e.g., colesevelam, cholestyramine, colestipol), Ion Exchange Resins (e.g., Kayexalate): Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer levothyroxine sodium tablets at least 4 hours prior to these drugs or monitor TSH levels.
Kidney
Confidence
low
Liver
Confidence
low
Elderly
Start at less than the full replacement dose in older adults because cardiovascular disease is more common. Atrial fibrillation is the most common arrhythmia seen with overtreatment in the elderly.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
8.5 Geriatric Use
Verbatim
Because of the increased prevalence of cardiovascular disease among the elderly, initiate levothyroxine sodium at less than the full replacement dose [see Dosage and Administration (2.3) and Warnings and Precautions (5.2)]. Atrial arrhythmias can occur in elderly patients. Atrial fibrillation is the most common of the arrhythmias observed with levothyroxine overtreatment in the elderly.
Missed dose
MedlinePlus says to take a missed dose as soon as you remember it, but skip it if it is almost time for the next dose, and never take a double dose. The label itself does not address missed doses.
Confidence
medium
Source text (exact source wording)
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What should I do if I forget a dose?
Verbatim
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Overdose
Overdose signs are those of hyperthyroidism, plus possible confusion and disorientation. Cerebral embolism, shock, coma and death have been reported, and seizures occurred in a 3-year-old who took 3.6 mg. Symptoms may not appear until several days after ingestion. Reduce the dose or stop temporarily and give supportive treatment. Call poison control at 1-800-222-1222; call 911 if the person has collapsed, had a seizure, has trouble breathing, or can't be awakened.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
10 OVERDOSAGE
Verbatim
The signs and symptoms of overdosage are those of hyperthyroidism [see Warnings and Precautions (5) and Adverse Reactions (6)]. In addition, confusion and disorientation may occur. Cerebral embolism, shock, coma, and death have been reported. Seizures occurred in a 3-year-old child ingesting 3.6 mg of levothyroxine. Symptoms may not necessarily be evident or may not appear until several days after ingestion of levothyroxine sodium.
Reduce the levothyroxine sodium dosage or discontinue temporarily if signs or symptoms of overdosage occur. Initiate appropriate supportive treatment as dictated by the patient’s medical status.
For current information on the management of poisoning or overdosage, contact the National Poison Control Center at 1-800-222-1222 or www.poison.org.
Reduce the levothyroxine sodium dosage or discontinue temporarily if signs or symptoms of overdosage occur. Initiate appropriate supportive treatment as dictated by the patient’s medical status.
For current information on the management of poisoning or overdosage, contact the National Poison Control Center at 1-800-222-1222 or www.poison.org.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
In case of emergency/overdose
Verbatim
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.
Storage
Store at 20° to 25°C (68° to 77°F), with excursions permitted between 15° to 30°C (59° to 86°F), protected from light and moisture. Keep out of reach of children. Storage can differ by labeler.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
16 HOW SUPPLIED/STORAGE AND HANDLING, Storage and Handling
Verbatim
Store Levothyroxine sodium tablets, USP at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Levothyroxine sodium tablets, USP should be protected from light and moisture.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What should I know about storage and disposal of this medication?
Verbatim
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).
Boxed warning
Thyroid hormones, including levothyroxine, should not be used to treat obesity or for weight loss. In people with normal thyroid levels, doses within the range of daily hormonal requirements do not work for weight loss. Larger doses may cause serious or even life-threatening toxicity, particularly with sympathomimetic amines used for their anorectic effects.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
Boxed Warning (full prescribing information), heading 'WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS'
Verbatim
Thyroid hormones, including levothyroxine sodium, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss.
In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction.
Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects [see Adverse Reactions (6), Drug Interactions (7.7), and Overdosage (10)].
In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction.
Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects [see Adverse Reactions (6), Drug Interactions (7.7), and Overdosage (10)].
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
Highlights, Boxed Warning
Verbatim
Thyroid hormones, including levothyroxine sodium, should not be used for the treatment of obesity or for weight loss.
Doses beyond the range of daily hormonal requirements may produce serious or even life-threatening manifestations of toxicity (6, 10).
Doses beyond the range of daily hormonal requirements may produce serious or even life-threatening manifestations of toxicity (6, 10).
Contraindications
Do not use in patients with uncorrected adrenal insufficiency.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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Section
4 CONTRAINDICATIONS
Verbatim
Levothyroxine sodium tablets are contraindicated in patients with uncorrected adrenal insufficiency [see Warnings and Precautions (5.4)].
Warnings and precautions
Levothyroxine has a narrow therapeutic index. Too much or too little can affect growth and development, heart, bone, reproductive, cognitive and gut function, and glucose and lipid metabolism. In children, undertreatment may harm cognitive development and growth, and overtreatment is linked to craniosynostosis and faster bone age. Titrate carefully and watch for food and drug interactions.
Heading
5.1 Serious Risks Related to Overtreatment or Undertreatment with Levothyroxine Sodium
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
5.1
Verbatim
Levothyroxine sodium has a narrow therapeutic index. Overtreatment or undertreatment with levothyroxine sodium may have negative effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, gastrointestinal function, and glucose and lipid metabolism in adult or pediatric patients.
In pediatric patients with congenital and acquired hypothyroidism, undertreatment may adversely affect cognitive development and linear growth, and overtreatment is associated with craniosynostosis and acceleration of bone age [see Use in Specific Populations (8.4)].
Titrate the dose of levothyroxine sodium carefully and monitor response to titration to avoid these effects [see Dosage and Administration (2.4)]. Consider the potential for food or drug interactions and adjust the administration or dosage of levothyroxine sodium as needed [see Dosage and Administration (2.1), Drug Interactions (7.1), and Clinical Pharmacology (12.3)].
In pediatric patients with congenital and acquired hypothyroidism, undertreatment may adversely affect cognitive development and linear growth, and overtreatment is associated with craniosynostosis and acceleration of bone age [see Use in Specific Populations (8.4)].
Titrate the dose of levothyroxine sodium carefully and monitor response to titration to avoid these effects [see Dosage and Administration (2.4)]. Consider the potential for food or drug interactions and adjust the administration or dosage of levothyroxine sodium as needed [see Dosage and Administration (2.1), Drug Interactions (7.1), and Clinical Pharmacology (12.3)].
Over-treatment may raise heart rate and cardiac contractility and may cause angina or arrhythmias, mainly in people with cardiovascular disease and the elderly, so start at lower doses. If cardiac symptoms develop or worsen, reduce the dose or withhold for one week and restart lower.
Heading
5.2 Cardiac Adverse Reactions in the Elderly and in Patients with Underlying Cardiovascular Disease
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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Section
5.2
Verbatim
Over-treatment with levothyroxine may cause an increase in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias, particularly in patients with cardiovascular disease and in elderly patients. Initiate levothyroxine sodium therapy in this population at lower doses than those recommended in younger individuals or in patients without cardiac disease [see Dosage and Administration (2.3) and Use in Specific Populations (8.5)].
Monitor for cardiac arrhythmias during surgical procedures in patients with coronary artery disease receiving suppressive levothyroxine sodium therapy. Monitor patients receiving concomitant levothyroxine sodium and sympathomimetic agents for signs and symptoms of coronary insufficiency.
If cardiac symptoms develop or worsen, reduce the levothyroxine sodium dose or withhold for one week and restart at a lower dose.
Monitor for cardiac arrhythmias during surgical procedures in patients with coronary artery disease receiving suppressive levothyroxine sodium therapy. Monitor patients receiving concomitant levothyroxine sodium and sympathomimetic agents for signs and symptoms of coronary insufficiency.
If cardiac symptoms develop or worsen, reduce the levothyroxine sodium dose or withhold for one week and restart at a lower dose.
Oral thyroid hormone is not recommended for myxedema coma; use products formulated for intravenous administration.
Heading
5.3 Myxedema Coma
Confidence
high
Source text (exact source wording)
Source
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Section
5.3
Verbatim
Myxedema coma is a life-threatening emergency characterized by poor circulation and hypometabolism and may result in unpredictable absorption of levothyroxine sodium from the gastrointestinal tract. Use of oral thyroid hormone drug products is not recommended to treat myxedema coma. Administer thyroid hormone products formulated for intravenous administration to treat myxedema coma.
Starting thyroid hormone before glucocorticoids may precipitate acute adrenal crisis in adrenal insufficiency, so treat with replacement glucocorticoids first.
Heading
5.4 Acute Adrenal Crisis in Patients with Concomitant Adrenal Insufficiency
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
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https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
5.4
Verbatim
Thyroid hormone increases metabolic clearance of glucocorticoids. Initiation of thyroid hormone therapy prior to initiating glucocorticoid therapy may precipitate an acute adrenal crisis in patients with adrenal insufficiency. Treat patients with adrenal insufficiency with replacement glucocorticoids prior to initiating treatment with levothyroxine sodium [see Contraindications (4)].
In diabetes, levothyroxine may worsen blood sugar control and raise antidiabetic agent or insulin needs; monitor glycemic control after starting, changing or stopping it.
Heading
5.5 Worsening of Diabetic Control
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
5.5
Verbatim
Addition of levothyroxine therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control after starting, changing, or discontinuing levothyroxine sodium [see Drug Interactions (7.2)].
Over-replacement may increase bone resorption and decrease bone mineral density, particularly in post-menopausal women. Use the minimum dose that achieves the desired response.
Heading
5.6 Decreased Bone Mineral Density Associated with Thyroid Hormone Over-Replacement
Confidence
high
Source text (exact source wording)
Source
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Url
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Section
5.6
Verbatim
Increased bone resorption and decreased bone mineral density may occur as a result of levothyroxine over-replacement, particularly in post-menopausal women. The increased bone resorption may be associated with increased serum levels and urinary excretion of calcium and phosphorous, elevations in bone alkaline phosphatase, and suppressed serum parathyroid hormone levels. Administer the minimum dose of levothyroxine sodium that achieves the desired clinical and biochemical response to mitigate this risk.
Pregnancy and breastfeeding
Clinical experience has not reported increased rates of major birth defects, miscarriages, or other adverse maternal or fetal outcomes with oral levothyroxine used to maintain a euthyroid state, and untreated hypothyroidism in pregnancy carries risks. Pregnancy may increase requirements, so TSH is monitored and the dose adjusted, and the dose returns to the pre-pregnancy dose right after delivery. Levothyroxine should not be discontinued during pregnancy. It is present in human milk and no adverse effects on the breastfed infant have been reported.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
8.1 Pregnancy, Risk Summary
Verbatim
The clinical experience, including data from postmarketing studies, in pregnant women treated with oral levothyroxine to maintain euthyroid state have not reported increased rates of major birth defects, miscarriages, or other adverse maternal or fetal outcomes. There are risks to the mother and fetus associated with untreated hypothyroidism in pregnancy. Since TSH levels may increase during pregnancy, TSH should be monitored and levothyroxine sodium dosage adjusted during pregnancy (see Clinical Considerations). Animal reproductive studies have not been conducted with levothyroxine sodium. Levothyroxine sodium should not be discontinued during pregnancy and hypothyroidism diagnosed during pregnancy should be promptly treated.
Source
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Url
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Section
8.1 Dose Adjustments During Pregnancy and the Postpartum Period
Verbatim
Pregnancy may increase levothyroxine sodium requirements. Serum TSH levels should be monitored and the levothyroxine sodium dosage adjusted during pregnancy. Since postpartum TSH levels are similar to preconception values, the levothyroxine sodium dosage should return to the pre-pregnancy dose immediately after delivery [see Dosage and Administration (2.3)].
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
2.3 Hypothyroidism in Pregnant Patients
Verbatim
For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range.
Source
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Url
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Section
8.2 Lactation, Risk Summary
Verbatim
Published studies report that levothyroxine is present in human milk following the administration of oral levothyroxine. No adverse effects on the breastfed infant have been reported and there is no information on the effects of levothyroxine on milk production. Adequate levothyroxine treatment during lactation may normalize milk production in hypothyroid lactating mothers with low milk supply. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for levothyroxine sodium and any potential adverse effects on the breastfed infant from levothyroxine sodium or from the underlying maternal condition.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What special precautions should I follow?
Verbatim
tell your doctor if you are pregnant, plan to become pregnant or are breastfeeding. If you become pregnant while taking levothyroxine, call your doctor.
Side effects
Common
Side effects are mainly those of hyperthyroidism due to too high a dose. The label lists them by body system (for example fatigue, increased appetite, weight loss, heat intolerance, headache, nervousness, insomnia, tremors, palpitations, diarrhea, hair loss, rash, menstrual irregularities) but gives no percentages or most-common threshold.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
Highlights, Adverse Reactions
Verbatim
Adverse reactions associated with levothyroxine sodium therapy are primarily those of hyperthyroidism due to therapeutic overdosage: arrhythmias, myocardial infarction, dyspnea, muscle spasm, headache, nervousness, irritability, insomnia, tremors, muscle weakness, increased appetite, weight loss, diarrhea, heat intolerance, menstrual irregularities, and skin rash. (6)
Source
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Url
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Section
6 ADVERSE REACTIONS
Verbatim
Adverse reactions associated with levothyroxine sodium therapy are primarily those of hyperthyroidism due to therapeutic overdosage [see Warnings and Precautions (5) and Overdosage (10)]. They include the following:
General: fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating
Central nervous system: headache, hyperactivity, nervousness, anxiety, irritability, emotional lability, insomnia
Musculoskeletal: tremors, muscle weakness, muscle spasm
Cardiovascular: palpitations, tachycardia, arrhythmias, increased pulse and blood pressure, heart failure, angina, myocardial infarction, cardiac arrest
Respiratory: dyspnea
Gastrointestinal: diarrhea, vomiting, abdominal cramps, elevations in liver function tests
Dermatologic: hair loss, flushing, rash
Endocrine: decreased bone mineral density
Reproductive: menstrual irregularities, impaired fertility
General: fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating
Central nervous system: headache, hyperactivity, nervousness, anxiety, irritability, emotional lability, insomnia
Musculoskeletal: tremors, muscle weakness, muscle spasm
Cardiovascular: palpitations, tachycardia, arrhythmias, increased pulse and blood pressure, heart failure, angina, myocardial infarction, cardiac arrest
Respiratory: dyspnea
Gastrointestinal: diarrhea, vomiting, abdominal cramps, elevations in liver function tests
Dermatologic: hair loss, flushing, rash
Endocrine: decreased bone mineral density
Reproductive: menstrual irregularities, impaired fertility
Less common
Seizures have been reported rarely when starting levothyroxine. Partial hair loss may occur rarely during the first few months but is usually temporary.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
6
Verbatim
Seizures have been reported rarely with the institution of levothyroxine therapy.
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Section
17
Verbatim
Inform patients that partial hair loss may occur rarely during the first few months of levothyroxine sodium tablets therapy, but this is usually temporary.
Serious
Label
In children, pseudotumor cerebri and slipped capital femoral epiphysis have been reported, and overtreatment may cause craniosynostosis in infants and premature closure of the epiphyses. Hypersensitivity reactions to inactive ingredients (including urticaria, angioedema and wheezing) have occurred; hypersensitivity to levothyroxine itself is not known to occur. Overdose has been linked to cerebral embolism, shock, coma and death.
Confidence
high
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
6 Adverse Reactions in Pediatric Patients
Verbatim
Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving levothyroxine therapy. Overtreatment may result in craniosynostosis in infants who have not undergone complete closure of the fontanelles, and in premature closure of the epiphyses in pediatric patients still experiencing growth with resultant compromised adult height.
Source
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Url
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Section
6 Hypersensitivity Reactions
Verbatim
Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various gastrointestinal symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness, and wheezing. Hypersensitivity to levothyroxine itself is not known to occur.
Source
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Url
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Section
10 OVERDOSAGE
Verbatim
Cerebral embolism, shock, coma, and death have been reported.
Medlineplus
MedlinePlus says to call your doctor immediately or get emergency care for shortness of breath, wheezing, hives, itching, rash, flushing, stomach pain, nausea, or swelling of the hands, feet, ankles or lower legs, and to tell your doctor about chest pain, rapid or irregular heartbeat, uncontrollable shaking, nervousness, anxiety, irritability, trouble sleeping, shortness of breath or excessive sweating.
Confidence
high
Source text (exact source wording)
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What side effects can this medication cause?
Verbatim
Some side effects can be serious. If you experience either of the following symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately or get emergency medical treatment:
shortness of breath, wheezing, hives, itching, rash, flushing, stomach pain, nausea, or swelling of hands, feet, ankles, or lower legs
shortness of breath, wheezing, hives, itching, rash, flushing, stomach pain, nausea, or swelling of hands, feet, ankles, or lower legs
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
IMPORTANT WARNING
Verbatim
Tell your doctor if you have any of the following symptoms while you are taking levothyroxine: chest pain, rapid or irregular heartbeat or pulse, uncontrollable shaking of a part of the body, nervousness, anxiety, irritability, difficulty falling asleep or staying asleep, shortness of breath, or excessive sweating.
Led to discontinuation
Note
The label gives no discontinuation-due-to-adverse-reaction data.
Confidence
high
Interactions
Drugs
These drugs can reduce levothyroxine absorption and may cause hypothyroidism. Give it at least 4 hours apart from phosphate binders, at least 4 hours before bile acid sequestrants and ion exchange resins (or monitor TSH), and monitor patients using orlistat, sucralfate, antacids or proton pump inhibitors.
Name
Phosphate binders, orlistat, bile acid sequestrants, ion exchange resins, proton pump inhibitors, sucralfate, antacids (decrease T4 absorption)
Section
7.1 Table 5
Source text (exact source wording)
Source
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Url
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Section
7.1 Table 5
Verbatim
Potential impact: Concurrent use may reduce the efficacy of levothyroxine sodium by binding and delaying or preventing absorption, potentially resulting in hypothyroidism.
Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum): Phosphate binders may bind to levothyroxine. Administer levothyroxine sodium tablets at least 4 hours apart from these agents.
Orlistat: Monitor patients treated concomitantly with orlistat and levothyroxine sodium for changes in thyroid function.
Bile Acid Sequestrants (e.g., colesevelam, cholestyramine, colestipol), Ion Exchange Resins (e.g., Kayexalate): Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer levothyroxine sodium tablets at least 4 hours prior to these drugs or monitor TSH levels.
Proton Pump Inhibitors Sucralfate Antacids (e.g., aluminum & magnesium hydroxides, simethicone): Gastric acidity is an essential requirement for adequate absorption of levothyroxine. Sucralfate, antacids and proton pump inhibitors may cause hypochlorhydria, affect intragastric pH, and reduce levothyroxine absorption. Monitor patients appropriately.
Phosphate Binders (e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum): Phosphate binders may bind to levothyroxine. Administer levothyroxine sodium tablets at least 4 hours apart from these agents.
Orlistat: Monitor patients treated concomitantly with orlistat and levothyroxine sodium for changes in thyroid function.
Bile Acid Sequestrants (e.g., colesevelam, cholestyramine, colestipol), Ion Exchange Resins (e.g., Kayexalate): Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer levothyroxine sodium tablets at least 4 hours prior to these drugs or monitor TSH levels.
Proton Pump Inhibitors Sucralfate Antacids (e.g., aluminum & magnesium hydroxides, simethicone): Gastric acidity is an essential requirement for adequate absorption of levothyroxine. Sucralfate, antacids and proton pump inhibitors may cause hypochlorhydria, affect intragastric pH, and reduce levothyroxine absorption. Monitor patients appropriately.
Phenobarbital and rifampin can increase levothyroxine metabolism. Amiodarone inhibits conversion of T4 to T3. Carbamazepine, phenytoin, furosemide (over 80 mg IV), heparin and some NSAIDs can displace thyroid hormone from protein binding; total and free T4 may drop by 20% to 40% with phenytoin and carbamazepine. Closely monitor thyroid hormone parameters.
Name
Drugs that alter T4 transport, metabolism or conversion (Tables 6 to 8)
Section
7.1 Tables 6-8
Source text (exact source wording)
Source
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Url
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Section
7.1 Table 7
Verbatim
Phenobarbital, Rifampin: Phenobarbital has been shown to reduce the response to thyroxine. Phenobarbital increases L-thyroxine metabolism by inducing uridine 5’-diphospho-glucuronosyltransferase (UGT) and leads to lower T4 serum levels. Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. Rifampin has been shown to accelerate the metabolism of levothyroxine.
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
7.1 Table 8
Verbatim
Other drugs: Amiodarone: Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.
Source
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Url
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Section
7.1 Table 6
Verbatim
Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-inflammatory Drugs - Fenamates: These drugs may cause protein-binding site displacement. [...] Phenytoin and carbamazepine reduce serum protein binding of levothyroxine, and total and free T4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid. Closely monitor thyroid hormone parameters.
May worsen glycemic control and raise antidiabetic agent or insulin needs.
Name
Antidiabetic therapy
Section
7.2
Source text (exact source wording)
Source
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Url
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Section
7.2
Verbatim
Addition of levothyroxine sodium therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control, especially when thyroid therapy is started, changed, or discontinued [see Warnings and Precautions (5.5)].
Levothyroxine increases the response to oral anticoagulants, so the anticoagulant dose may need to be decreased and coagulation tests monitored closely.
Name
Oral anticoagulants
Section
7.3
Source text (exact source wording)
Source
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Url
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Section
7.3
Verbatim
Levothyroxine sodium increases the response to oral anticoagulant therapy. Therefore, a decrease in the dose of anticoagulant may be warranted with correction of the hypothyroid state or when the levothyroxine sodium dose is increased. Closely monitor coagulation tests to permit appropriate and timely dosage adjustments.
May reduce the effects of digitalis glycosides; their dose may need to increase when a hypothyroid patient becomes euthyroid.
Name
Digitalis glycosides
Section
7.4
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
7.4
Verbatim
Levothyroxine sodium may reduce the therapeutic effects of digitalis glycosides. Serum digitalis glycoside levels may decrease when a hypothyroid patient becomes euthyroid, necessitating an increase in the dose of digitalis glycosides.
Tricyclic or tetracyclic antidepressants may increase the effects and toxicity of both drugs, including arrhythmias and CNS stimulation. Sertraline may increase levothyroxine requirements.
Name
Antidepressants (tricyclic, tetracyclic, sertraline)
Section
7.5
Source text (exact source wording)
Source
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Url
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Section
7.5
Verbatim
Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and levothyroxine sodium may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. Toxic effects may include increased risk of cardiac arrhythmias and central nervous system stimulation. Levothyroxine sodium may accelerate the onset of action of tricyclics. Administration of sertraline in patients stabilized on levothyroxine sodium may result in increased levothyroxine sodium requirements.
May produce marked hypertension and tachycardia; monitor blood pressure and heart rate.
Name
Ketamine
Section
7.6
Source text (exact source wording)
Source
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Url
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Section
7.6
Verbatim
Concurrent use of ketamine and levothyroxine sodium may produce marked hypertension and tachycardia. Closely monitor blood pressure and heart rate in these patients.
May increase the effects of sympathomimetics or thyroid hormone, and the risk of coronary insufficiency in coronary artery disease.
Name
Sympathomimetics
Section
7.7
Source text (exact source wording)
Source
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Url
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Section
7.7
Verbatim
Concurrent use of sympathomimetics and levothyroxine sodium may increase the effects of sympathomimetics or thyroid hormone. Thyroid hormones may increase the risk of coronary insufficiency when sympathomimetic agents are administered to patients with coronary artery disease.
May cause hypothyroidism; monitor TSH closely.
Name
Tyrosine-kinase inhibitors (e.g., imatinib)
Section
7.8
Source text (exact source wording)
Source
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Url
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Section
7.8
Verbatim
Concurrent use of tyrosine-kinase inhibitors such as imatinib may cause hypothyroidism. Closely monitor TSH levels in such patients.
Food and alcohol
Soybean flour, cottonseed meal, walnuts and dietary fiber may bind levothyroxine and decrease absorption, and grapefruit juice may delay absorption and reduce bioavailability. Talk to your doctor before eating or drinking these foods.
Name
Soybean flour, cottonseed meal, walnuts, dietary fiber, grapefruit juice
Section
7.9
Source text (exact source wording)
Source
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Url
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Section
7.9 Drug-Food Interactions
Verbatim
Consumption of certain foods may affect levothyroxine sodium absorption thereby necessitating adjustments in dosing [see Dosage and Administration (2.1)]. Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of levothyroxine sodium from the gastrointestinal tract. Grapefruit juice may delay the absorption of levothyroxine and reduce its bioavailability.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What special dietary instructions should I follow?
Verbatim
Some foods and beverages, particularly those that contain soybeans, walnuts, and dietary fiber, may affect how levothyroxine works for you. Talk to your doctor before eating or drinking these foods.
Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medication.
Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medication.
Coffee is not addressed in the label or MedlinePlus text read.
Name
Coffee
Section
label and MedlinePlus
Alcohol is not addressed in the label or MedlinePlus text read.
Name
Alcohol
Section
label and MedlinePlus
Other
Biotin can cause erroneous thyroid hormone test results. Stop biotin and biotin-containing supplements for at least 2 days before thyroid testing.
Name
Biotin
Section
2.4; 7.10
Source text (exact source wording)
Source
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Url
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Section
7.10 Drug-Laboratory Test Interactions, Biotin
Verbatim
Biotin supplementation is known to interfere with thyroid hormone immunoassays that are based on a biotin and streptavidin interaction, which may result in erroneous thyroid hormone test results. Stop biotin and biotin-containing supplements for at least 2 days prior to thyroid testing.
Iron and calcium supplements and antacids can decrease absorption. Do not take levothyroxine within 4 hours of them.
Name
Iron and calcium supplements, antacids
Section
17
Source text (exact source wording)
Source
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Url
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Section
17 Dosing and Administration
Verbatim
Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine. Instruct patients not to take levothyroxine sodium tablets within 4 hours of these agents.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What special precautions should I follow?
Verbatim
if you take calcium carbonate (Tums) or ferrous sulfate (iron supplement), take it at least 4 hours before or 4 hours after you take levothyroxine.
Patient tips
Label patient counseling
Take it only as directed, as a single dose, preferably on an empty stomach one-half to one hour before breakfast, and not within 4 hours of iron, calcium or antacids. It may take several weeks to notice improvement, replacement therapy is generally for life, and it should not be used for weight control. Stop biotin at least 2 days before thyroid tests and tell your surgeon or dentist you take it. Tell your provider about a rapid or irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleeplessness, tremors, appetite or weight change, vomiting, diarrhea, excessive sweating, heat intolerance, fever, menstrual changes, hives or rash.
Source text (exact source wording)
Source
DailyMed NorthStar levothyroxine label (printer-friendly page)
Url
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Section
17 PATIENT COUNSELING INFORMATION
Verbatim
Dosing and Administration
Instruct patients to take levothyroxine sodium tablets only as directed by their healthcare provider.
Instruct patients to take levothyroxine sodium tablets as a single dose, preferably on an empty stomach, one-half to one hour before breakfast.
Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine. Instruct patients not to take levothyroxine sodium tablets within 4 hours of these agents.
Instruct patients to notify their healthcare provider if they are pregnant or breastfeeding or are thinking of becoming pregnant while taking levothyroxine sodium tablets.
Important Information
Inform patients that it may take several weeks before they notice an improvement in symptoms.
Inform patients that the levothyroxine in levothyroxine sodium tablets is intended to replace a hormone that is normally produced by the thyroid gland. Generally, replacement therapy is to be taken for life.
Inform patients that levothyroxine sodium tablets should not be used as a primary or adjunctive therapy in a weight control program.
Instruct patients to notify their healthcare provider if they are taking any other medications, including prescription and over-the-counter preparations.
Instruct patients to discontinue biotin or any biotin-containing supplements for at least 2 days before thyroid function testing is conducted.
Instruct patients to notify their physician or dentist that they are taking levothyroxine sodium tablets prior to any surgery.
Adverse Reactions
Instruct patients to notify their healthcare provider if they experience any of the following symptoms: rapid or irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleeplessness, tremors, change in appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, heat intolerance, fever, changes in menstrual periods, hives or skin rash, or any other unusual medical event.
Instruct patients to take levothyroxine sodium tablets only as directed by their healthcare provider.
Instruct patients to take levothyroxine sodium tablets as a single dose, preferably on an empty stomach, one-half to one hour before breakfast.
Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine. Instruct patients not to take levothyroxine sodium tablets within 4 hours of these agents.
Instruct patients to notify their healthcare provider if they are pregnant or breastfeeding or are thinking of becoming pregnant while taking levothyroxine sodium tablets.
Important Information
Inform patients that it may take several weeks before they notice an improvement in symptoms.
Inform patients that the levothyroxine in levothyroxine sodium tablets is intended to replace a hormone that is normally produced by the thyroid gland. Generally, replacement therapy is to be taken for life.
Inform patients that levothyroxine sodium tablets should not be used as a primary or adjunctive therapy in a weight control program.
Instruct patients to notify their healthcare provider if they are taking any other medications, including prescription and over-the-counter preparations.
Instruct patients to discontinue biotin or any biotin-containing supplements for at least 2 days before thyroid function testing is conducted.
Instruct patients to notify their physician or dentist that they are taking levothyroxine sodium tablets prior to any surgery.
Adverse Reactions
Instruct patients to notify their healthcare provider if they experience any of the following symptoms: rapid or irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleeplessness, tremors, change in appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, heat intolerance, fever, changes in menstrual periods, hives or skin rash, or any other unusual medical event.
Medlineplus
MedlinePlus says to take tablets with a full glass of water, that levothyroxine controls hypothyroidism but does not cure it, to continue taking it even if you feel well, not to stop without talking to your doctor, and not to switch brands without talking to your doctor or pharmacist.
Source text (exact source wording)
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
How should this medicine be used?
Verbatim
Take the tablets with a full glass of water as they may get stuck in your throat or cause choking or gagging.
Levothyroxine controls hypothyroidism but does not cure it. It may take several weeks before you notice a change in your symptoms. Continue to take levothyroxine even if you feel well. Do not stop taking levothyroxine without talking to your doctor.
Levothyroxine controls hypothyroidism but does not cure it. It may take several weeks before you notice a change in your symptoms. Continue to take levothyroxine even if you feel well. Do not stop taking levothyroxine without talking to your doctor.
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Section
What other information should I know?
Verbatim
Learn the brand name and generic name of your medication. Do not switch brands without talking to your doctor or pharmacist, as each brand of levothyroxine contains a slightly different amount of medication.
Alternatives
Class
thyroid hormone (L-thyroxine, T4)
Class source
Source
DailyMed NorthStar label Highlights
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Verbatim
Levothyroxine sodium tablets are a L-thyroxine (T4) indicated in adult and pediatric patients, including neonates, for:
Source
MedlinePlus levothyroxine
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Verbatim
Levothyroxine is in a class of medications called hormones.
Indication
hypothyroidism (label section 1)
Confidence
low
Frequently asked questions
Question
What is levothyroxine used for?
Answer
It is replacement therapy for primary, secondary and tertiary hypothyroidism in adults and children, including newborns, and an add-on to surgery and radioiodine therapy for thyrotropin-dependent well-differentiated thyroid cancer.
Source section
1 INDICATIONS AND USAGE
Source
DailyMed NorthStar label
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Question
How and when should I take it?
Answer
Take it as a single daily dose on an empty stomach, one-half to one hour before breakfast, and at least 4 hours before or after drugs that interfere with absorption.
Source section
2.1
Source
DailyMed NorthStar label
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Question
What if I miss a dose?
Answer
MedlinePlus says to take it as soon as you remember, but to skip the missed dose if it is almost time for the next one, and never to take a double dose.
Source section
What should I do if I forget a dose?
Source
MedlinePlus
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Question
Do grapefruit or certain foods affect it?
Answer
Soybean flour, cottonseed meal, walnuts and dietary fiber may decrease absorption, and grapefruit juice may delay absorption and reduce bioavailability.
Source section
7.9
Source
DailyMed NorthStar label
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Question
Can I use it for weight loss?
Answer
No. Thyroid hormones should not be used to treat obesity or for weight loss, and larger doses may produce serious or even life-threatening toxicity.
Source section
Boxed Warning
Source
DailyMed NorthStar label
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Question
Is it safe in pregnancy and breastfeeding?
Answer
It should not be discontinued during pregnancy, and pregnancy may increase requirements so TSH is monitored. Levothyroxine is present in human milk and no adverse effects on the breastfed infant have been reported.
Source section
8.1; 8.2
Source
DailyMed NorthStar label
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Question
What should I not take at the same time?
Answer
Do not take levothyroxine within 4 hours of iron or calcium supplements or antacids. Biotin should be stopped at least 2 days before thyroid tests.
Source section
17
Source
DailyMed NorthStar label
Url
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=58f4dc90-3648-49dc-a7e1-baf918a773b5&type=display
Question
Should I stop taking it when I feel well?
Answer
No. MedlinePlus says to continue to take levothyroxine even if you feel well and not to stop without talking to your doctor. The label says replacement therapy is generally taken for life.
Source section
How should this medicine be used?; 17
Source
MedlinePlus; DailyMed NorthStar label
Url
https://medlineplus.gov/druginfo/meds/a682461.html
Sources
- Levothyroxine Sodium Tablets, NorthStar Rx LLC (ANDA211417; manufactured by Macleods Pharmaceuticals Limited) CHOSEN generic label
Set id: 58f4dc90-3648-49dc-a7e1-baf918a773b5 · Label effective or revised date: Highlights 'Revised: 8/2026' (char 4701); Section 17 'Revised: August 2026' (char 51844); footer 'Revised: 8/2026' (char 68440) · Dailymed version date: Updated August 20, 2026; listing published Aug 21, 2026 (WebFetch) · Fetched at: 2026-11-02 · Sections used: Highlights, boxed warning, 1-8, 10, 11, 12, 16, 17 verbatim from printer-friendly page - MedlinePlus: Levothyroxine
Set id: n/a · Label effective or revised date: Last Revised - 02/15/2019 · Fetched at: 2026-11-02 · Sections used: all patient sections - ALTERNATE 1: Levothyroxine tablets, Lupin Pharmaceuticals, Inc. (ANDA209713)
Set id: 18717e58-89fb-4e2f-93b6-d6ac3e988d37 · Label effective or revised date: Highlights 'Revised: 3/2025' (WebFetch extract) · Fetched at: 2026-11-02 · Sections used: date, category only - ALTERNATE 2: Levothyroxine tablets, Accord Healthcare Inc. (ANDA212399)
Set id: a6233381-3043-4e9a-aaa6-a6b105e5142b · Label effective or revised date: Highlights 'Revised: 6/2024' (WebFetch extract; Teva ANDA207588, set ID 60cadfd7-82b5-4207-97e1-1dd0655efb27, same date) · Fetched at: 2026-11-02 · Sections used: date, category only - SYNTHROID brand label, AbbVie Inc. (NDA021402)
Set id: 1e11ad30-1041-4520-10b0-8f9d30d30fcc · Label effective or revised date: Revised: 2/2024 (WebFetch extract) · Fetched at: 2026-11-02 · Sections used: differences only - Other labels checked by WebFetch for date/category only
Set id: Alvogen NDA021116 4ddcaec1-a58f-340b-9bc1-bbe048b8c885 (Revised 3/2026, NDA so excluded by label rule); Mylan Institutional ANDA076187 cd69c192-cd3f-47e6-b0a6-c536ffed5c4b (4/2024); Lannett NDA authorized generic NDA021342 a8db0f7d-8863-9309-e053-2995a90a284a (7/2020); Amneal NY NDA authorized generic NDA021210 fca88c97-5cd4-4834-ba87-deb5bd637788 (Highlights date not visible) · Label effective or revised date: as listed · Fetched at: 2026-11-02 · Sections used: date only - Drugs@FDA
Set id: n/a · Label effective or revised date: NOT FOUND · Fetched at: 2026-11-02 · Sections used: NOT FOUND: search returned no result rows
Information is taken from the cited sources and is for general reference only. It is not medical advice. Report side effects to FDA MedWatch at 1-800-FDA-1088. For a poison emergency call 1-800-222-1222. See prices for this drug