Allopurinol is one of the most used medicines to lower uric acid and prevent gout attacks. If you’ve had painful gout flares, kidney stones from uric acid, or very high urate levels on blood tests, this drug is often the first choice. Below you'll find simple, useful info on how it works, what to watch for, and how to use it safely.
Allopurinol blocks xanthine oxidase, the enzyme that makes uric acid. Less uric acid means fewer crystals in joints and fewer gout attacks over time. Doctors prescribe it when you have recurring gout, tophi (visible deposits), uric acid kidney stones, or very high uric acid on labs. It’s not a pain reliever for an active attack — it prevents future attacks.
People with frequent flares or chronic gout, and those with kidney stones from urate, are common candidates. If you have severe kidney disease or certain genetic risks, your doctor may do extra tests (see HLA-B*5801 below).
Typical starting dose is 100 mg daily. Many clinicians increase by 100 mg every few weeks until uric acid drops below the target (usually <6 mg/dL; <5 mg/dL when tophi are present). Common maintenance doses are 200–300 mg/day. Doses can go higher, but doctors adjust carefully.
If you have reduced kidney function, the dose is lowered or increased slowly under supervision. Your doctor will check kidney function, liver tests, and serum uric acid before and during treatment. Regular follow-up matters: the goal is a specific uric acid number, not just taking a pill.
When starting allopurinol you may get more gout flares at first. That’s normal. Doctors often give a short course of colchicine or an NSAID to reduce flare risk during the first 3 months.
Watch for red flags. Stop the drug and seek urgent care if you get a widespread rash, fever, sore throat, or worsening liver or kidney tests. A small number of people develop a severe reaction (allopurinol hypersensitivity syndrome) that can be life-threatening. Certain ethnic groups (Korean, Han Chinese, Thai) have a higher risk; testing for HLA-B*5801 is sometimes recommended before starting.
Know key drug interactions: allopurinol raises levels of azathioprine and mercaptopurine — these combinations can be dangerous. Tell your doctor about all medicines, especially thiopurines and certain cancer drugs. Stay hydrated to help kidneys and reduce stone risk.
Practical tips: take tablets with a glass of water, keep regular follow-up labs, don’t stop suddenly without talking to your doctor, and use preventive colchicine during the first months if advised. If you’re unsure about dosing or interactions, call your prescriber — small adjustments and monitoring make allopurinol much safer and more effective.
