How to Use the Drug Interaction Checker
- Enter the name of your first medication in the search field above
- Enter the name of your second medication
- Review instant interaction information powered by NIH RxNorm data
- Always confirm findings with your pharmacist or prescribing doctor before making any medication changes
The RxDiff drug interaction checker covers thousands of FDA-approved prescription and over-the-counter medications. It checks for pharmacokinetic interactions (where one drug changes how the body processes another), pharmacodynamic interactions (where drugs have additive or opposing effects), and contraindications documented in clinical literature.
Common Drug Interaction Examples
Some of the most frequently searched drug interaction pairs include:
- Warfarin + Aspirin — both thin the blood; combined use significantly increases bleeding risk
- SSRIs + Tramadol — can increase serotonin syndrome risk; 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
These are illustrative examples only — always check your specific medications and doses with this tool and your healthcare provider.
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. Interactions can be drug-drug (two prescriptions), drug-food (a medication and something you eat or drink), or drug-condition (a medication that affects a health condition differently). Some interactions are mild; others can be dangerous — always consult your pharmacist or doctor before combining medications.
How reliable is this drug interaction checker?
RxDiff's drug interaction checker is powered by the NIH RxNorm database, a trusted medication terminology system used by healthcare professionals, pharmacies, and insurance systems nationwide. While this tool provides clinically relevant interaction data, it is not a substitute for professional medical advice. Your pharmacist has access to your complete medication history and is the best resource for personalized interaction 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?
The current tool checks one pair of drugs at a time. If you take multiple medications, check each combination separately — for example, if you take Drug A, B, and C, check A+B, A+C, and B+C. Your pharmacist can perform a comprehensive multi-drug interaction review for your complete medication list.
Does the drug interaction checker include supplements and OTC medications?
Yes — the NIH RxNorm database includes many over-the-counter medications (ibuprofen, acetaminophen, antacids, antihistamines) and some common supplements. Coverage varies — if your supplement is not found, ask your pharmacist about known interactions for that ingredient.