Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are: febuxostat, other drugs that weaken the immune system/increase the risk of infection (such as rituximab, tofacitinib).

This medication may interfere with certain lab tests (such as uric acid levels), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

Mercaptopurine is very similar to azathioprine. Do not use medications containing azathioprine while using mercaptopurine.