Allopurinol and Amoxicillin and clavulanate interaction
Allopurinol and Amoxicillin and clavulanate: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Allopurinol label · effective 2026-05-21
Concomitant use of the following drugs may also increase the risk of skin rash, which may be severe: bendamustine, ampicillin and amoxicillin [ see Drug Interactions (7.1) ].
The following drugs may increase the risk of serious skin reactions: bendamustine, thiazide diuretics, ampicillin and amoxicillin.
Drugs Known to Affect the Occurrence of Skin Rash and Hypersensitivity Concomitant use of the following drugs may increase the risk of skin rash, which may be severe: bendamustine, thiazide diuretics, ampicillin and amoxicillin.
From the Amoxicillin and clavulanate (Amoxicillin and Clavulanate Potassium) label · effective 2026-07-07
Co-administration with allopurinol increases the risk of rash.
Allopurinol The concurrent administration of allopurinol and amoxicillin substantially increases the incidence of rashes in patients receiving both drugs as compared to patients receiving amoxicillin alone.
However, this sample size is too small to allow for any conclusions to be drawn regarding the risk of rashes with concomitant Amoxicillin and Clavulanate Potassium Extended Release Tablets and allopurinol use.
It is not known whether this potentiation of amoxicillin rashes is due to allopurinol or the hyperuricemia present in these patients.
In controlled clinical trials of Amoxicillin and Clavulanate Potassium Extended Release Tablets, 25 patients received concomitant allopurinol and Amoxicillin and Clavulanate Potassium Extended Release Tablets.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.