Mercaptopurineinteractions
mercaptopurine 50 MG Oral Tablet
This is the interactions section of this product’s FDA label — what the manufacturer documented for this drug. It is not a check of your medication list, and a drug missing from it has not been cleared: licensed clinical databases list far more interactions than any single label does. Before combining medicines, ask a pharmacist, who can check everything you take at once and will do it for free.
Named on this label
Every name above is printed in the text below. This is not the full set of drugs that interact with this one — it is the set this manufacturer wrote down.
Drug interactions
Allopurinol: Reduce the dose of Mercaptopurine Tablets when co-administered with allopurinol.
Warfarin: Mercaptopurine Tablets may decrease the anticoagulant effect.
7.1 Allopurinol
Allopurinol can inhibit the first-pass oxidative metabolism of mercaptopurine by xanthine oxidase, which can lead to an increased risk of mercaptopurine adverse reactions (i.e., myelosuppression, nausea, and vomiting). Reduce the dose of Mercaptopurine Tablets when coadministered with allopurinol.
7.2 Warfarin
The concomitant administration of Mercaptopurine Tablets and warfarin may decrease the anticoagulant effectiveness of warfarin. Monitor the international normalized ratio (INR) in patients receiving warfarin and adjust the warfarin dosage as appropriate.
7.3 Myelosuppressive
Products Mercaptopurine Tablets can cause myelosuppression. Myelosuppression may be increased when Mercaptopurine Tablets are coadministered with other products that cause myelosuppression. Enhanced myelosuppression has been noted in some patients also receiving trimethoprim-sulfamethoxazole. Monitor the CBC and adjust the dose of Mercaptopurine Tablets for excessive myelosuppression.
7.4 Aminosalicylates
Aminosalicylates (e.g., mesalamine, olsalazine or sulfasalazine) may inhibit the TPMT enzyme, which may increase the risk of myelosuppression when coadministered with Mercaptopurine Tablets. When aminosalicylates and Mercaptopurine Tablets are coadministered, use the lowest possible doses for each drug and monitor more frequently for myelosuppression.
7.5 Hepatotoxic
Products Mercaptopurine Tablets can cause hepatotoxicity. Hepatotoxicity may be increased when Mercaptopurine Tablets are coadministered with other products that cause hepatotoxicity. Monitor liver tests more frequently in patients who are receiving Mercaptopurine Tablets with other hepatotoxic products.
Text above is quoted in full from the FDA-approved drug label published by openFDA, effective February 25, 2026. Matched to this product by RxNorm code. Cross-references to other sections of the full prescribing information have been removed, since they point to a document not shown here. Nothing else is changed: no sentence is shortened, reworded or summarised.
This page reproduces regulatory text for reference. It is not medical advice, and KenyRx is not a pharmacy or a prescriber. Talk to a doctor or pharmacist about whether a medicine is right for you.
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