Allopurinol: What it does and what you should know

Allopurinol is one of the most common drugs used to lower uric acid. Doctors prescribe it for gout prevention, some types of kidney stones, and long-term high uric acid levels. It doesn’t stop an active gout attack right away, but it lowers the risk of future flares when used correctly.

Here you’ll get straightforward facts: how it works, how to take it, who needs dose changes, and what to watch for. No fluff—just the things patients ask about every day.

Dosing basics and kidney advice

Typical starting doses are 100 mg a day, often increased gradually to 300 mg a day. Some people need higher doses, up to 600–800 mg daily, but that’s decided by a doctor based on uric acid levels and response. If you have reduced kidney function, your prescriber will usually start lower and raise the dose more slowly.

Why the slow increase? Two reasons: fewer side effects and lower risk of the rare but serious allopurinol hypersensitivity. If you’re of Han Chinese, Thai, or Korean ancestry and have kidney disease, ask your doctor about HLA-B*5801 testing before starting—this genetic marker raises that hypersensitivity risk.

Side effects, interactions, and simple monitoring

Common side effects are mild: stomach upset, headache, and minor rashes. A new rash while on allopurinol should never be ignored—tell your doctor right away. Rare but severe reactions can affect skin, liver, and kidneys and require stopping the drug immediately.

Important drug interactions: allopurinol can raise levels of azathioprine and mercaptopurine, so those drugs shouldn’t be combined without close medical oversight. Thiazide diuretics may increase rash risk. If you take blood thinners, diabetes meds, or other chronic drugs, mention allopurinol to your pharmacist so they can check interactions.

Monitoring is simple: your doctor will check uric acid levels, kidney function (creatinine), and sometimes liver tests. If you start allopurinol, expect follow-up blood tests and a plan to adjust the dose until uric acid is at the target range.

Practical tips: take allopurinol with food if it upsets your stomach, stay well hydrated to help the kidneys, and don’t stop the medicine suddenly if you feel better—stopping can trigger flares. If you have an active gout flare, your clinician may delay dose changes or use short-term anti-inflammatory protection while the urate-lowering therapy continues or starts, depending on your situation.

Allopurinol is prescription-only. Buy from reputable pharmacies and keep a current medication list for every provider you see. If you have questions about dosing with kidney problems, possible genetic testing, or drug interactions, ask your doctor or pharmacist—those small checks make treatment safer and more effective.

Want more detail or real-world tips? Check with your care team and compare notes during your next visit. Simple monitoring and clear communication go a long way with allopurinol.