Interaction Checker

Free. No account. No ads.

Drug interaction checker that shows its sources

Add your medicines, supplements, and habits. Every result quotes the FDA prescribing label it came from, so you can see exactly what the manufacturer says before you talk to your pharmacist.

550+ drugs, 42,000+ documented pairs Supplements, food, alcohol included Your list never leaves your browser

Type a name and press Enter. Add everything you take, then read the results below.

Try an example or start typing above. Brand names like Tylenol, Advil, or Zoloft work too.

How it works

The same method runs on every pair, in the browser, in a fraction of a second.

1. Two labels, read both ways

For each pair, the checker reads the boxed warning, contraindications, warnings, and drug interaction sections of both FDA labels and looks for the other drug by name or by drug class.

2. Graded by the label's own words

A hit in a boxed warning or contraindications, or words like contraindicated and avoid, grades Major. Monitoring or dose instructions grade Moderate. A plain mention grades Minor.

3. Quoted, not summarized

You see the actual sentence, which section it sits in, and a link to the full label on DailyMed. Supplement and food rules cite the NIH or FDA page they come from.

What the severity levels mean

Major

Contraindicated, boxed warning, or the label says to avoid the combination. Talk to a prescriber before taking both.

Moderate

The label calls for monitoring, a dose adjustment, or spacing the doses apart. Often manageable, rarely ignorable.

Minor

The other drug or its class is mentioned without an instruction to avoid it or change the dose.

No significant interaction

The label explicitly reports no clinically significant interaction. Still worth confirming for your doses.

Commonly checked combinations

Each page shows the verdict and the label sentences behind it.

Browse all drugs A to ZSupplements, food, and alcohol

Frequently asked questions

Where does the interaction data come from?
From the FDA prescribing labels published through openFDA and DailyMed. For each pair, the checker scans the boxed warning, contraindications, warnings, and drug interactions sections of both labels for a mention of the other drug by name or by drug class, and shows you the exact sentence. Supplement, food, and alcohol rules are drawn from NIH Office of Dietary Supplements and NCCIH fact sheets and FDA consumer guidance.
How is the severity decided?
By where the mention appears and how it is worded. A mention in a boxed warning or contraindications section, or wording such as contraindicated, avoid, or not recommended, is graded Major. Wording that calls for monitoring, a dose change, or spacing the doses is Moderate. A mention without an instruction is Minor. If the label explicitly reports no clinically significant interaction, the pair is marked accordingly.
What does it mean when nothing is documented?
It means neither label mentions the other drug or its class, and no curated rule applies. Labels are not exhaustive, so this is not proof that a combination is safe. Ask a pharmacist, especially for newer drugs or for more than a few medicines at once.
Can I check brand names, supplements, or alcohol?
Yes. Type a brand such as Tylenol, Zoloft, or Advil and the checker maps it to the generic. Supplements, vitamins, minerals, common foods such as grapefruit and dairy, alcohol, tobacco, and cannabis are included as items you can add to your list.
Is my medication list private?
Your list is kept in your browser's local storage and in the page address if you copy a link. It is never sent to our servers. The one exception is the optional FDA lookup for drugs outside our list, which queries api.fda.gov directly from your browser.
Is this a replacement for talking to a pharmacist?
No. This is a fast way to see what the official labels say before you ask. Dose, kidney and liver function, age, and other conditions change how an interaction matters, and only a clinician who knows your history can weigh that.

Not medical advice. This tool summarizes publicly available label text. It cannot account for your doses, kidney or liver function, age, pregnancy, or other conditions. Confirm any concern with a pharmacist or prescriber before changing how you take a medicine. Read the guide to drug interactions and how results are generated.