Allopurinol Dosage: What You Need to Know

If you’ve been prescribed allopurinol, the biggest question is usually “how much should I take?” The answer depends on why you’re taking it, how your kidneys work, and whether you’re an adult or a child. Below we break down the most common dosing schedules, give you simple tips on taking the pill, and point out the safety tweaks you shouldn’t miss.

Typical adult dosing for gout and high uric acid

For most adults with gout or chronic high uric acid, doctors start you on 100 mg once a day. After a week or two they may bump the dose up by 100 mg every 2‑4 weeks until your blood uric‑acid level is under 6 mg/dL. Most people end up on 300 mg‑600 mg a day, split into two doses (morning and evening). The highest dose on the market is 800 mg per day, but that’s only for people who haven’t reached target levels even on 600 mg.

Why split the dose? Allopurinol works best when your body gets a steady amount of the drug. Taking it twice a day keeps the blood level more even and reduces the chance of a sudden flare‑up.

Kidney function matters

Your kidneys clear allopurinol, so if they’re not working well you’ll need a lower dose. The rule of thumb is:

• Creatinine clearance > 60 mL/min: regular adult dose (100‑300 mg daily).
• 30‑60 mL/min: start at 100 mg daily, max 300 mg.
• Less than 30 mL/min: 50‑100 mg daily, and watch for side effects.

Doctors will check your kidney numbers before setting the dose and may re‑check after a month.

Pediatric dosing

Kids with gout or tumor‑related uric‑acid spikes get a dose based on weight. The usual start is 5‑10 mg per kilogram of body weight per day, divided into two doses. For example, a 30‑kg child might start at 150‑300 mg daily (75‑150 mg each dose). Pediatric doctors adjust the dose based on blood tests, just like with adults.

How to take allopurinol for best results

Take the pill with food or right after a meal – this cuts stomach upset. If you’re on a split dose, try to keep the times around the same each day (e.g., 8 a.m. and 8 p.m.). Avoid alcohol while loading the dose; drinking can trigger a gout flare even if your uric‑acid level looks good.

Stay hydrated. Drinking plenty of water helps flush excess uric acid and keeps the kidneys happy. Aim for at least 8 glasses a day unless your doctor tells you otherwise.

Common side effects and when to call the doctor

Most people tolerate allopurinol well. Mild rash or stomach trouble is the usual complaint. If a rash spreads or you feel feverish, it could be a rare but serious allergy called Stevens‑Johnson syndrome – seek medical help right away.

Other red flags: sudden severe stomach pain, unexplained bruising, or yellowing of the skin. Those could signal liver or blood‑cell problems and need prompt attention.

Key drug interactions

Allopurinol can boost the effect of certain antibiotics (like ampicillin) and chemotherapy drugs (like azathioprine). If you’re on those, your doctor may lower the dose of the other medication. Also, keep an eye on warfarin – allopurinol can make your blood thinner, so more frequent INR checks might be needed.

Bottom line: start low, go slow, and let your doctor fine‑tune the dose based on blood tests. Follow the timing tips, stay hydrated, and watch for rash or stomach pain. With the right dose, allopurinol can keep uric‑acid levels in check and prevent painful gout attacks.