Allopurinol: What It Does and Who Needs It
Allopurinol is a xanthine oxidase inhibitor that lowers uric acid. Doctors most often prescribe it for gout, recurrent uric acid kidney stones, or very high uric acid after cancer treatment. It doesn’t stop a sudden gout attack, but it helps prevent future attacks by lowering the uric acid that forms crystals in joints and kidneys.
How allopurinol works and who should consider it
Allopurinol blocks the enzyme that makes uric acid. If you have frequent gout flares, visible tophi, kidney stones from uric acid, or chronic high uric acid levels above target, your provider may suggest it. People starting cancer therapy that can spike uric acid (tumor lysis) sometimes get allopurinol as prevention. Talk with your clinician if you have kidney disease, liver issues, or are pregnant — dosing and risks change.
Dosing, monitoring, and safety tips
Typical starting doses are 100 mg once daily for most adults. With normal kidneys, many patients are raised to 200–300 mg daily and sometimes higher if needed. The maximum is generally 800 mg per day split into doses. If you have reduced kidney function, clinicians start lower (sometimes 50 mg) and increase slowly. The goal is a serum uric acid under about 6 mg/dL; labs guide how high to go.
Expect more gout flares in the first 3–6 months after starting or changing the dose. That’s normal. Doctors often give low-dose colchicine (0.5 mg daily) or an NSAID for the first few months to prevent flares.
Get a baseline basic metabolic panel and liver tests before starting. Repeat checks while you adjust dose, then periodically once stable. Stop the drug and call your provider right away for any rash, fever, swollen glands, or new muscle pain — these can signal a serious reaction called allopurinol hypersensitivity syndrome, which needs urgent care.
One important safety note: certain people have a higher risk of severe skin reactions. Testing for the HLA-B*5801 gene is recommended in people of Han Chinese, Korean, or Thai ancestry, and in others with risk factors. If positive, doctors usually avoid allopurinol.
Watch for drug interactions. Allopurinol increases levels of azathioprine and mercaptopurine — those doses must be cut or avoided. It can also alter effects of some chemotherapy drugs and require closer monitoring with blood thinners like warfarin. Always tell providers every medicine you take, including over-the-counter drugs and supplements.
Practical tips: take allopurinol with food if it upsets your stomach, keep regular lab follow-up, and don’t stop the medicine suddenly after repeated gout attacks without talking to your doctor. If allopurinol causes trouble or isn’t strong enough, there are alternatives such as febuxostat or uricosuric drugs — your clinician can explain options based on your heart and kidney health.
If you want a clearer plan for starting or adjusting allopurinol, print your recent labs and bring them to your visit. That makes dose decisions easier and keeps your treatment moving in the right direction.
