How to Use the Drug Interaction Checker
RxDiff's drug interaction checker compares two medication names by matching them with NIH RxNorm and finding relevant interaction statements in openFDA drug labels. The result is a starting point for a medication conversation, not a substitute for advice from a pharmacist or prescribing doctor.
- Enter the name of your first medication in the search field above.
- Enter the name of your second medication.
- Review interaction statements from openFDA drug labels that mention the other selected medication.
- Confirm findings with your pharmacist or prescribing doctor before making medication changes.
Label coverage varies, so the checker may not surface every clinically important interaction.
Common Drug Interaction Examples
RxDiff's drug interaction checker examples illustrate medication pairs that can raise safety concerns, including bleeding, serotonin syndrome, lactic acidosis, higher statin levels, and dangerous potassium levels. These examples are illustrative only: check the medications and doses you take, then discuss findings with your healthcare provider.
- Warfarin + Aspirin: Both thin the blood; combined use significantly increases bleeding risk.
- SSRIs + Tramadol: Can increase serotonin syndrome risk and requires medical supervision.
- Metformin + Alcohol: Increases risk of lactic acidosis; alcohol should be limited.
- Statins + Grapefruit juice: Grapefruit can raise statin blood levels, increasing side effect risk.
- ACE inhibitors + Potassium supplements: Can raise potassium to dangerous levels.
Common Questions About Drug Interactions
What is a drug interaction?
A drug interaction occurs when two medications affect each other's effectiveness or cause unexpected side effects when taken together. Drug interactions can also involve food, drinks, or a health condition; some are mild, while others can be dangerous and should be discussed with a pharmacist or doctor.
Drug-drug: Two prescription medications interact. Drug-food: A medication interacts with something you eat or drink. Drug-condition: A medication affects a health condition differently.
How reliable is this drug interaction checker?
RxDiff's drug interaction checker finds relevant statements available in openFDA drug-label records after NIH RxNorm matches medication names and concepts, but it is not a complete clinical review. Results may not include every interaction or account for dose, conditions, or a full medication list; a pharmacist or prescriber can provide personalized guidance.
Is it free to check drug interactions?
Yes. The RxDiff drug interaction checker is completely free — no account, sign-up, or insurance required. You can check as many medication pairs as you need.
Can I check more than two drugs at once?
RxDiff checks drug interactions one pair of drugs at a time; it cannot review more than two medicines in one check. For Drug A, B, and C, check A+B, A+C, and B+C separately, and ask a pharmacist for a comprehensive multi-drug interaction review of your complete medication list.
Does the drug interaction checker include supplements and OTC medications?
Medication-name coverage depends on NIH RxNorm matching, while interaction text depends on whether an openFDA label record contains relevant information. Many supplements do not have comparable FDA drug-label interaction sections; ask your pharmacist about supplement interactions.
