Allopurinol: What It Is, How It Works, and What You Need to Know

When your body makes too much allopurinol, a xanthine oxidase inhibitor used to lower uric acid levels in the blood. Also known as Zyloprim, it’s one of the most prescribed drugs for people with recurring gout or kidney stones caused by excess uric acid.

Allopurinol doesn’t treat pain during a gout flare—it stops future flares by blocking the enzyme that turns purines into uric acid. That’s key. If you eat a lot of red meat, shellfish, or drink beer regularly, your body breaks down purines into uric acid, which can crystallize in your joints and cause swelling, heat, and sharp pain. Allopurinol cuts that process at the source. It’s not a quick fix, but it’s a long-term solution that many people rely on for years without major issues.

People taking allopurinol often also deal with hyperuricemia, a condition where uric acid levels in the blood stay too high. Left unchecked, it doesn’t just cause gout—it can damage kidneys, lead to tophi (painful lumps under the skin), and increase the risk of heart disease. That’s why doctors often prescribe allopurinol even if you haven’t had a full gout attack yet. It’s preventative medicine at its most straightforward.

Not everyone tolerates allopurinol well. Some get a rash, nausea, or dizziness. A rare but serious reaction called allopurinol hypersensitivity syndrome can affect the liver or skin, especially in people with kidney problems or certain genetic markers. That’s why starting low and going slow matters. Your doctor will likely begin with 100 mg a day and adjust based on your blood tests and how you feel.

Allopurinol doesn’t work alone. It’s often part of a bigger plan. Many people combine it with dietary changes—cutting back on organ meats, sugary drinks, and alcohol. Staying hydrated helps flush out uric acid. Some also take colchicine, a drug used to prevent or treat gout flares during the first few months of starting allopurinol, because lowering uric acid too fast can trigger a flare. It’s counterintuitive, but it’s normal.

There are alternatives, like febuxostat, which works similarly but may be used if allopurinol causes side effects. But for most people, allopurinol remains the first choice because it’s been around for decades, works reliably, and is cheap. Generic versions are widely available, making it one of the most cost-effective long-term treatments for chronic gout.

What you’ll find below are real patient experiences and clinical insights about allopurinol—how it fits into daily life, what side effects to watch for, how it interacts with other meds like diuretics or aspirin, and when it might not be the right choice. No fluff. Just clear, practical info from people who’ve been there and doctors who’ve seen the results.