How do I check drug interactions online?

Use this free drug interaction checker by typing the names of the medications you are taking, including prescription drugs, over-the-counter medicines, and supplements. The tool will analyze all possible pairs and show conflicts ranked by severity (critical, high, moderate, low) along with the mechanism and clinical recommendation. Always consult your doctor or pharmacist before making any changes.

How many drugs can I check at once?

You can add as many drugs as you need. The interaction checker will analyze every possible pair (so 5 drugs = 10 pair checks). Most patients only need to check 2-4 medications at a time, but the tool handles complex polypharmacy with 10+ drugs without performance loss.

Is this drug interaction checker free?

Yes — completely free, no registration required. PillsCard is an independent drug encyclopedia funded by affiliate partnerships with verified pharmacies. Our interaction database comes from FDA labels, EMA, DDInter (clinical pharmacology research) and SemMedDB (PubMed-mined evidence), totaling 130,000+ substance pairs and 547,000+ drug-pair interactions.

What does each severity level mean?

Critical (red) — life-threatening interactions, never combine. High (orange) — clinically significant, requires monitoring or alternative therapy. Moderate (yellow) — adjustments may be needed (timing, dosage). Low (green) — minor interactions, usually no action required but worth knowing about.

Can this tool replace my pharmacist or doctor?

No. This is an information tool, not medical advice. A pharmacist or doctor knows your full medical history, age, kidney/liver function, and other context that affects interaction risk. Always consult them before adding, removing, or changing any medication.

Where does the interaction data come from?

We aggregate data from regulatory bodies (FDA OpenFDA, EMA), peer-reviewed databases (DDInter from Tongji University, SemMedDB from NIH), and drug labels in official registries (URPL, BfArM, Swissmedic, etc.). All data is updated daily via automated parsers. Each interaction has a tier indicator showing source quality.

What is a drug-drug interaction?

A drug-drug interaction (DDI) occurs when one medication changes the effect of another. This can be pharmacokinetic (one drug affects how another is absorbed, distributed, metabolized, or excreted) or pharmacodynamic (drugs interact at the receptor or system level). Some interactions are beneficial (combination therapy), but most flagged here are harmful or require dose adjustment.

Does this checker include herbal supplements and OTC drugs?

Yes — our database includes major herbal supplements (St. John's Wort, ginkgo, ginseng), vitamins (vitamin K with warfarin, etc.), and over-the-counter products (NSAIDs, acetaminophen). Search for the active ingredient or product name.

Drug Interaction Checker

Check if your medications interact. Add 2 or more drugs and get a detailed compatibility report.

Add Drugs to Check

Add at least 2 drugs to check interactions

How to Use the Interaction Checker

1. Type a drug name in the search box and select it from the autocomplete suggestions.

2. Add at least 2 drugs you want to check for interactions.

3. Click 'Check Interactions' to see the results.

Results are color-coded by severity: critical (red), high (orange), moderate (yellow), low (green).

This information is for educational purposes only. It is not intended as medical advice. Always consult a qualified healthcare professional.

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