20 medicines. Every pair.
Check up to 20 medications together — up to 190 pairs in a single check.
FDA + NIH data. Built around you.
Check drug interactions.
Understand your medicines.
Check my medications ↓- 20 medicines · 190 pairs
- Brand/generic autocomplete
- Phone label scan
- Text, email & WhatsApp sharing
Powerful drug information. Plain language. More confidence.
Your medicines deserve a clear explanation. CDI brings FDA drug labeling and NIH drug-name data together in one easy-to-use checker, designed for patients and the people who care for them.
Free to check. No account required.
Your medication check starts here
Add your medicines. See the connections.
Enter up to 20 medications to check for interactions.
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- FDA labels processed
- 257,570
- Interaction records
- 22,180
- Medications in one check
- 20
Original import corpus · May 2026
Database snapshot · November 10, 2026
Up to 190 medication pairs
One medicine. The information you need.
Look up its interactions, label warnings, and related medicines.
Built for patients. Made for everyday life.
More convenience.
More clarity. That’s CDI.
Compare CDI with Drugs.com, WebMD & Medscape →Autocomplete that helps you find it
Start typing a brand or generic name. Choose a matching medicine from the suggestions.
Your phone is a label scanner
Use your camera or upload a label photo, then confirm the matching medicine. Less typing, more convenience.
Bring your care team into the picture
Share a medication-check link by text, WhatsApp, email, or copy-and-paste. Help family and caregivers stay informed.
Plain language. Priorities first.
See severity-ranked interaction results, everyday explanations, and expandable source information.
Your lists, ready for next time
Sign in to save named medication lists and access them across devices. Reuse recent medicines as you build a list.
Go deeper on one medicine
Use Single Drug Lookup to explore interactions, label warnings, and related medicines. Browse the drug library, too.
Open your browser. Start checking.
The checker, autocomplete, label scan, and sharing are free to use. No account or app download needed to check.
Public data. Public benefit.
Comprehensive drug information,
made human.
FDA drug labels contain valuable information that everyone should be able to understand. We processed 257,570 labels to build a searchable interaction database and turn technical wording into useful, everyday explanations.
See our sources and original import →U.S. FDADrug labeling through openFDANIH / NLMStandardized drug names through RxNorm
Designed for youPatients, families, and caregivers at the center
Drug information belongs in your hands.
Making publicly funded drug information genuinely accessible to the public.
We are building the most comprehensive, patient-friendly drug interaction resource on the web. Our mission starts with public FDA and NIH data: make it searchable, explain it clearly, and put patients and caregivers first.
What Are Drug Interactions?
A drug interaction occurs when one medication alters the way another works in your body — raising or lowering blood levels, amplifying side effects, or blocking the intended effect altogether. Interactions can occur between two prescription medications, between a prescription and an over-the-counter drug, or between a drug and a food, supplement, or herbal product.
CDI organizes interaction information into five classifications: contraindicated, major, moderate, minor, and unknown. Clear descriptions help you understand what the source says and which questions to bring to your care team.
Use the results to prepare questions for your pharmacist or prescriber. Do not start, stop, or change a prescribed medication based solely on this tool.
Explore Source-Linked Explanations
These educational articles link to a specific source and section, explain its wording, and describe the limits of the explanation.
Why can grapefruit affect some statins?
Grapefruit can interfere with how the body handles certain medicines. The effect depends on the specific drug.
Why does warfarin labeling warn about aspirin?
Warfarin labeling lists aspirin among medicines that increase bleeding risk when taken with warfarin.
How Our Drug Interaction Checker Works
Enter any drug name — brand or generic — into the search fields above. Our autocomplete draws from the NIH RxNorm database to identify the canonical drug name and its RxCUI identifier. Once you have confirmed at least two drugs, click Check Interactions to see every pair evaluated simultaneously.
Results bring the information together: interaction summaries, severity classifications, explanations of how an interaction works when available, and the recorded source. AI-assisted summaries make technical label language easier to read.
The checker supports up to 20 drugs at once, with sharing designed for patients and caregivers. On mobile, you can photograph a pill bottle label and our OCR feature will extract and search the drug name automatically.
Frequently Asked Questions
What is a drug interaction?
A drug interaction occurs when one medication changes the way another medication works in your body. Interactions can increase a drug's side effects, reduce its effectiveness, or — in serious cases — cause life-threatening reactions. They can happen between two prescription drugs, between a prescription and an over-the-counter drug, or between a drug and a food or supplement.
How serious are drug interactions?
CDI displays contraindicated, major, moderate, minor, and unknown classifications. These summarize source wording and are not an individual risk assessment. Unknown means the severity has not been established in the record; it does not mean safe.
Where does your interaction data come from?
CDI primarily uses FDA drug labeling via openFDA, with NIH/NLM RxNorm for drug identities. Limited curated-reference records are explicitly tagged. Source text, extracted summaries, and educational explanations are distinct; see our methodology for details.
Can I check more than two drugs at once?
Yes. Add up to 20 medications and CDI checks every pair — up to 190 combinations — in one step. Results include interaction summaries, severity classifications, and source information.
Does "no interaction found" mean it's safe to take both?
It means CDI did not find a matching interaction record. It is not a guarantee of safety. Your pharmacist or physician can assess your exact medicines, doses, and health circumstances.
Is this tool a substitute for talking to my pharmacist?
No. checkdruginteractions.com is an informational reference tool. Your pharmacist has access to your full medication history and can apply clinical judgment to your specific situation. This tool helps you arrive at that conversation informed — not replace it.