allopurinol vs warfarin
Side-by-side comparison of allopurinol and warfarin. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
minor Known Drug Interaction
Warfarin Clinical Impact Allopurinol may inhibit the metabolism of warfarin, possibly enhancing its anticoagulant effect. Assess INR frequently and adjust warfarin dosage accordingly when allopurinol is added to warfarin therapy.
Recommendation: Your doctor should check your blood clotting levels (INR) frequently and adjust your warfarin dose if necessary.
Zyloprim
Coumadin, Jantoven
Allopurinol is a medicine that lowers uric acid levels in your body. It helps prevent gout attacks and other problems caused by high uric acid.
Warfarin is a medicine that helps prevent blood clots. It is used to treat and prevent dangerous clots from forming in your body.
This medicine is used to manage gout in adults. Gout causes painful attacks, joint damage, and kidney problems. Allopurinol is also used in adults and children with leukemia, lymphoma, and solid tumors who are getting cancer treatment. It helps manage high uric acid caused by the cancer treatment. It can also help adults who get calcium oxalate kidney stones often.
Warfarin is used to prevent and treat blood clots in your veins and lungs. It can also prevent clots if you have atrial fibrillation (irregular heartbeat) or a replacement heart valve. After a heart attack, it can lower the risk of death, another heart attack, or a stroke.
Allopurinol works by blocking an enzyme called xanthine oxidase. This enzyme helps your body make uric acid. By blocking it, allopurinol reduces the amount of uric acid in your blood and urine.
Warfarin works by blocking your body's use of vitamin K. Vitamin K is needed to make blood clotting factors. By blocking vitamin K, warfarin makes your blood less likely to clot.
- • Diarrhea
- • Nausea
- • Increased liver enzyme levels
- • Gout attacks
- • Skin rash
- • Bleeding from any tissue or organ
- Diarrhea 8,423
- Tiredness 7,965
- Difficulty breathing 7,659
- Feeling sick to your stomach 7,061
- Death 6,664
- INR increased 10,275
- Shortness of breath 8,408
- Interaction with another medicine 6,289
- Tiredness 6,141
- Feeling sick to your stomach 5,921
Allopurinol can cause serious skin reactions that can be deadly. Stop taking this medicine and get medical help right away if you get a skin rash or any other signs of an allergic reaction.
Warfarin can cause major or fatal bleeding. You must have your blood tested regularly (INR) while taking warfarin. Many things, like other medicines and diet changes, can affect your INR. Tell your doctor about any bleeding and follow their instructions to prevent bleeding.
Allopurinol may harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is not recommended to breastfeed while taking this medicine because it can pass into breast milk.
Warfarin can harm your unborn baby, especially during the first three months of pregnancy. Do not take warfarin if you are pregnant, unless you have a mechanical heart valve and your doctor says the benefits outweigh the risks. Talk to your doctor if you are breastfeeding, and watch your baby for bruising or bleeding.
Also Compare, Nearby Drugs
Compare allopurinol with
How to Read This allopurinol vs warfarin Comparison
allopurinol is classified in the Xanthine Oxidase Inhibitor drug class, while warfarin sits within the Vitamin K Antagonist (Anticoagulant) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, allopurinol has 37,772 submissions while warfarin has 37,034. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to allopurinol slows down the body's ability to break down warfarin. this can cause warfarin to stay in the body longer and increase the risk of bleeding.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between allopurinol and warfarin - always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.