Does Allopurinol Interact With Azathioprine?
Concomitant use with allopurinol increases the exposure of either mercaptopurine or azathioprine which may increase the risk of myelosuppression.
Severity: Moderate
Severity basis: warnings section (keywords: may increase). Combining Allopurinol (Xanthine oxidase inhibitor) and Azathioprine (Immunosuppressant) is classified as a moderate interaction.
What to Do
Use this combination with caution. Your prescriber may monitor you more closely or adjust doses.
From the FDA Label
Concomitant use with allopurinol increases the exposure of either mercaptopurine or azathioprine which may increase the risk of myelosuppression.
Source: FDA structured product labeling (set_id 005048dd-844f-468c-bf56-1a09727e3477).
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This information is educational — not medical advice.
This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.