Allopurinol is used for the treatment of hyperuricemia and gout. The most serious adverse reactions of allopurinol may cause exfoliative dermatitis, toxic epidermolysis bullosa, severe erythema multiforme drug rash, drug hypersensitivity syndrome, and in severe cases, death. Allopurinol may cause leukopenia or thrombocytopenia, anemia, and bone marrow suppression, in which case discontinuation should be considered, especially when allopurinol is combined with azathioprine, the side effect of bone marrow suppression is more pronounced, so it is important to note that the two drugs should not be combined. Allopurinol may also cause gastrointestinal symptoms, such as diarrhea, nausea, vomiting and abdominal pain.