Medication interaction checker

A medication-list checker built on official drug labels from the U.S. National Library of Medicine.

Know what your labels say — before your next refill.

List your medications, supplements, conditions and lab values. See, in the label's own words, where they meet.

My-Rx Check Sample list — not a real patient
5 medications · 3 supplements
2 conditions · 3 lab values
  • 3-wayWarfarin + Aspirin + Fish oil Use caution rule: bleeding risk adds up
  • Warfarin + Aspirin Use caution label: increased bleeding risk
  • Lisinopril + Spironolactone Use caution label: potassium may rise
  • Simvastatin + Grapefruit juice Talk to your pharmacist first label: avoid grapefruit juice
  • Warfarin + St. John's wort Use caution label: may reduce effect
  • Spironolactone + Potassium 5.6 (high) Talk to your pharmacist first label: contraindicated in hyperkalemia
  • Lisinopril + Chronic kidney disease (N18) Monitor label: monitor renal function
Each line links to the passage in the official label it came from. Ask your pharmacist
  • 6 kinds of check: duplicates, drug–drug, three-way combinations, supplements, conditions and labs
  • DailyMed every finding quotes the FDA-approved label published by NLM
  • ICD-10 conditions are matched by code prefix to contraindications and warnings
  • AES-256 for privacy, saved lists are encrypted; your email is stored only as a hash and ciphertext

The pad above is an illustration. Open the sample list to run the real check and read the passages.

Why My-Rx Check

More than a pair-by-pair lookup

New

Three-way combination detection

Some risks only appear when three or more medications are taken together — each pair looks fine, but the effects add up. The checker sorts every ingredient on your list into risk groups by its drug class and flags the combinations that cross the line, citing the source of each rule.

  • “Triple whammy” kidney risk
  • Opioid + sedatives
  • Bleeding risk
  • High potassium
  • Serotonin syndrome
  • Heart rhythm (QT)
  • Anticholinergic load
  • Falls in older adults
Each pair: at most a note. All three: “triple whammy” kidney-injury risk.

Official NLM sources

Every finding comes from free public services of the U.S. National Library of Medicine and NIH — no private database you can't check.

  • RxNorm
  • RxClass / MED-RT
  • DailyMed
  • ICD-10-CM
  • DSLD
  • MedlinePlus

Kept up to date

Label text is re-read from DailyMed at least every 30 days, and the labels the checker is tested on are compared with DailyMed's version history every month, so a revised label is picked up promptly.

See each source's data date

In the label's own words

Each finding quotes the passage it rests on and links to the full label, graded like the warning stickers on a pharmacy bottle.

Reads the fine print

“No dose adjustment is necessary” is not a warning. Reassuring sentences are set aside — and still shown — so they don't raise false alarms.

Tested every month

The checker is re-run monthly against drug pairs and combinations with known, referenced answers, and every change in its results is reviewed.

Conditions and lab values Subscribers

Add conditions by ICD-10 code or description and recent lab results; each label's contraindications and warnings are checked against them.

For everyone you look after Subscribers

Keep a separate, encrypted list for each person — up to 10 — and print the findings to take to the next appointment.

  • List

    Search medications by name and strength (RxNorm), add supplements, conditions by ICD-10 code, and recent lab values.

  • Check label-sourced

    Each drug's label and contraindication data are read and cross-referenced against everything else on your list — pair by pair, and as a whole for three-way combinations.

  • Ask

    Take the findings — each with its quoted passage and source — to your pharmacist or prescriber. Subscribers can print them.

How it works

  1. Build your list

    Type a few letters and pick the drug and strength. Five minutes with your pill bottles and your last lab report is enough.

  2. Run the check

    The checker reads the Drug interactions, Contraindications and Warnings sections of every label, looks for the rest of your list, and checks for risks that build up across three or more medications.

  3. Have the conversation

    Findings are graded like the warning stickers on a bottle and quote the label, so you know exactly what to ask about.

Learn more: where the data comes from, and what the check can and cannot do

Sources. Drug names, strengths and active ingredients come from RxNorm. Drug classes and the "contraindicated with" disease relationships come from RxClass / MED-RT. The text of each label comes from DailyMed. Condition names and codes come from the NLM ICD-10-CM search, and supplement products from the NIH Dietary Supplement Label Database. All are free public services of the National Library of Medicine and NIH.

Why labels? The National Library of Medicine retired its drug-interaction lookup service in January 2024. The FDA-approved label is the primary source that service was built on, and it is still published in full — so the checker goes to the label itself and shows you the passage, rather than a summary you cannot trace.

Three-way combinations. Some risks build up across several medications — an ACE inhibitor or ARB with a diuretic and an NSAID, or three drugs that each raise bleeding risk or potassium. No single label describes these, so each ingredient is placed in risk groups by its drug class (ATC, from RxClass) or by name, and published rules count how many fall in each group. Every rule cites its source; the full list is on the Reference tables page.

Keeping current. Each label's text is fetched again from DailyMed at least every 30 days. Every month the checker is re-run against a set of drug pairs and combinations whose answers are known and referenced, and DailyMed's version history is checked for revised labels; any change in results is reviewed.

Conditions. You pick a condition by its ICD-10 code. The code is matched by prefix to a lookup table (for example, every code starting N18 is chronic kidney disease), and the table's keywords are searched for in each drug's contraindications and warnings. The table is on the Reference tables page.

Lab values. Enter a result and it is compared with a typical adult range. When it is out of range, each label is searched for the words it uses for that abnormality — a high potassium for "hyperkalemia", a high INR for bleeding. The range printed on your own lab report always takes precedence.

Limits. This is a text search of official labeling, not a curated clinical database. It can miss an interaction a label words differently, and it can show a passage about a dose or a patient group that is not yours. No finding does not mean no interaction. It is a way to prepare for a conversation with a licensed professional — never a reason to start, stop or change a medication on your own.

Sign in with your email, then open a saved list or create a new one. Registered members can save 1 list; subscribers up to 10 — one for each person they look after — plus the condition and lab cross-checks.