DrugPair safety guide
Supplement and drug interaction checker
Check vitamins, minerals & herbal supplements against Rx and OTC medicines. St. John's Wort, fish oil, calcium & more.
Frequently asked questions
Common questions about supplement and drug interaction checker.
- Do supplements interact with prescription medicines?
- Yes. Common examples include St. John's Wort lowering levels of many medicines (including antidepressants and birth control), fish oil adding to bleeding risk with blood thinners, calcium reducing absorption of levothyroxine, and magnesium binding certain antibiotics. DrugPair checks supplements alongside all your medicines in one step.
- Which supplements should I always tell my doctor about?
- Particularly important ones to disclose include St. John's Wort, fish oil, vitamin E, ginkgo biloba, garlic supplements, valerian, and melatonin. These have well-documented interactions with commonly prescribed medicines. Always give your prescriber a complete list of everything you take, including vitamins.
- Are herbal supplements covered in DrugPair?
- Yes. DrugPair covers common herbal supplements including St. John's Wort, echinacea, garlic, ginkgo, valerian, and many more. Add them under the Supplements tab alongside your medicines.
- Is it safe to take multivitamins with any medicine?
- Most standard multivitamins are low-risk, but high-dose individual vitamins (vitamin K, vitamin E, iron) can affect specific medicines. Run a check in DrugPair with your exact supplement and medicine combination, and discuss the results with your pharmacist.
Related guides
Explore our free drug interaction checker and safety guides.
Free drug interaction checkerFood and drug interactionsSenior medication safety for familiesAlcohol and medication interaction checkerMetformin and Alcohol: What Diabetics Need to KnowCan I Take Ibuprofen and Acetaminophen Together?Blood Thinners and Green Vegetables: The Vitamin K Guide10 Common Drug Combinations to Avoid
Popular searches covered
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Written by DrugPair Editorial Team. Updated 16 July 2026. A licensed-clinician review is not yet documented; see the review policy.
General references: U.S. Food and Drug Administration, NIH MedlinePlus. Read the methodology and limitations.
DrugPair provides educational safety information only and is not a substitute for professional medical advice. Always ask a doctor or pharmacist before changing medicines, supplements, food, drinks, or prescription timing.