Allopurinol-100 Allopurinol Azathioprine
ModerateWhen allopurinol is taken with azathioprine, the azathioprine dose should be cut to 25% of the original dose. The leaflet's wording covers 6-mercaptopurine and Imruza, which are the same kind of drug, so the 25% rule applies to them too. Allopurinol can also come with its breakdown products, oxipurinol and thiopurinol, and the same reduction applies.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.