Allopurinol is a medication that reduces the production of uric acid in the body. It is used primarily to treat conditions caused by excess uric acid such as gout and certain types of kidney stones. By inhibiting the enzyme xanthine oxidase the drug lowers the conversion of hypoxanthine to uric acid. This reduction decreases the concentration of uric acid in the blood and tissues. The lower uric acid level helps prevent the formation of crystals that trigger inflammation and pain. The overall effect is a decrease in the frequency and severity of gout attacks and a reduced risk of stone recurrence.

Allopurinol is a medication that reduces the production of uric acid in the body by inhibiting the enzyme xanthine oxidase. This inhibition slows the conversion of hypoxanthine to xanthine and xanthine to uric acid, thereby lowering serum urate levels. The reduction of uric acid helps prevent the formation of crystal deposits that cause gout attacks and kidney stones. Pharmacodynamically the drug produces a dose-dependent decrease in uric acid concentration that is sustained for several hours after each dose. Its pharmacological profile includes renal clearance of the unchanged compound and hepatic metabolism of its active metabolite oxypurinol. The primary therapeutic effect is the prophylaxis and treatment of chronic gout and the management of recurrent kidney stones.

Allopurinol can cause skin rash in some patients. It may lead to mild nausea or vomiting. Some individuals experience headache or dizziness. Elevated liver enzymes can occur without noticeable symptoms. Kidney function may be affected in rare cases. Joint pain or swelling sometimes appears during treatment. Fatigue or low energy levels are reported by certain users. Allergic reactions that affect the skin can develop in a small number of cases.

The most frequently reported side effects include skin rash and itching. Some patients experience mild stomach discomfort or nausea. Headache is another common complaint reported in clinical studies. Drowsiness may occur, though it is less typical. Elevated liver enzymes are occasionally observed during treatment. Joint pain can appear, sometimes resembling gout attacks. Swelling of the lips or face has been noted in rare cases. Blood cell counts may decrease slightly, leading to increased infection risk.