DOSING: The dose of allopurinol for treating gout is 200-600 mg daily depending on severity. The dose for treating high uric acid blood levels due to chemotherapy is 100-800 mg daily starting 1 or 2 days before chemotherapy. It should be taken with food to avoid irritation of the stomach. In order to avoid formation of kidney stones, patients should drink plenty of fluids while taking allopurinol.
DRUG INTERACTIONS: Allopurinol increases blood levels of oral mercaptopurine (Purinethol) and azathioprine (Imuran) by reducing their breakdown in the body. Therefore, the dose of mercaptopurine and azathioprine should be reduced in order to avoid toxicity. There is an increased risk of skin rash in patients taking allopurinol in combination with penicillins. Allopurinol may increase the effect of warfarin by reducing its breakdown.
PREGNANCY: There are no adequate studies of allopurinol in pregnant women.
SIDE EFFECTS: Common reactions include diarrhea, nausea, rash and itching, and drowsiness. The most frequent side effect to allopurinol is skin rash. Allopurinol should be discontinued immediately at the first appearance of rash, painful urination, blood in the urine, eye irritation, or swelling of the mouth or lips, because these can be a signs of an impending severe allergic reaction that can be fatal. Allopurinol should be avoided by patients with a prior severe reaction to the drug. Allopurinol can cause a flare-up of gouty arthritis during initial therapy. Therefore, colchicine often is used simultaneously to prevent these flares.
Quick GuideGout Attack Symptoms, Causes, Treatment, and Diet
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