Medication · xanthine oxidase inhibitor

Supplements and Allopurinol.

Not yet catalogued in the Distil interactions database. We surface that distinction explicitly.

Allopurinol, sold under the brand name Zyloric, is a xanthine oxidase inhibitor used in gout.

Allopurinol is a xanthine oxidase inhibitor, used in gout to reduce urate production. UK prescribing centres on allopurinol, with febuxostat as an alternative when allopurinol is not tolerated. Mechanism is direct inhibition of the enzyme that converts hypoxanthine and xanthine to uric acid. The supplement surface is small but includes one notable drug interaction. Azathioprine and mercaptopurine clearance both depend on xanthine oxidase, so allopurinol potentiates their effect substantially and requires dose reduction when the two are prescribed together. The supplement-relevant points are mostly about urate handling. Vitamin C at high doses (above 1g/day) has a small uricosuric effect that can stack on top of xanthine oxidase inhibition. Cherry extract has weak evidence for additive urate lowering. The hypersensitivity rash (severe in a small minority) is a class-flagged adverse effect. It warrants prompt drug stop and review.

We have not yet completed an explicit assessment of supplement interactions with Allopurinol in the Distil database. That is different from saying nothing exists. We surface this distinction deliberately: the Distil checker tells you when we have explicitly assessed a pair and when we have not, because both are useful information. If you take Allopurinol alongside a supplement, the checker below will surface anything already in our database, and the missing-item form at the bottom of the page routes uncatalogued pairs into our next curation pass.

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.