Allopurinol — Gout Prevention Medication | KiwiMeds
✅ Reviewed by a Registered Pharmacist NZ | Last updated: May 2026 | This information is for educational purposes only and does not replace advice from your doctor or pharmacist.
What is allopurinol?
Allopurinol is a medicine used to prevent gout attacks by lowering the levels of uric acid in the blood. It is not a painkiller — it does not treat an acute gout attack, but when taken regularly it prevents future attacks from occurring. In New Zealand it is available as a generic.
What is it used for? (NZ context)
Allopurinol is used to prevent recurrent gout attacks, kidney stones caused by uric acid, and to lower uric acid in people receiving chemotherapy. It is prescribed for long-term use — often for life. It is fully funded by Pharmac.
How does it work?
Uric acid is formed when the body breaks down purines (found in red meat, seafood, and alcohol). Allopurinol blocks xanthine oxidase, an enzyme needed to produce uric acid. By lowering uric acid levels, it prevents urate crystals from forming in joints — the cause of gout pain.
How to take it
Allopurinol is taken once daily, usually starting at a low dose (100mg) and increasing slowly to reach a target uric acid level. Drink plenty of water. Do NOT start allopurinol during an acute gout attack — wait until the inflammation has settled. It takes weeks to months to see full benefit.
Common side effects
- Skin rash — stop immediately and see a doctor if this occurs
- Nausea or stomach upset
- Drowsiness
- Headache
Serious side effects to watch for
A severe skin reaction called Stevens-Johnson Syndrome is rare but serious. Seek urgent medical attention if you develop a widespread, painful rash with blistering or sores in the mouth. People of Han Chinese, Thai, or Korean descent have a higher genetic risk of this reaction.
Important drug interactions
Azathioprine and 6-mercaptopurine — allopurinol dramatically increases the effect of these immunosuppressants; doses must be reduced significantly. Warfarin — allopurinol may increase bleeding risk. ACE inhibitors — increased risk of hypersensitivity reactions.
NZ-specific information
Pharmac funding: Allopurinol 100mg and 300mg tablets are fully funded by Pharmac. It is one of the most cost-effective gout prevention medicines available in NZ.
Frequently asked questions
Can allopurinol make gout worse at first?
Yes — when you first start allopurinol, gout attacks may temporarily increase as uric acid crystals are mobilised. Doctors often prescribe colchicine or an anti-inflammatory to take alongside allopurinol for the first few months.
Do I take allopurinol during a gout attack?
No — do not start allopurinol during an acute attack. Wait until the flare has fully settled (usually 2–4 weeks). If you are already on allopurinol when an attack starts, continue taking it.
How long do I need to take allopurinol?
Allopurinol is usually taken long-term, often for life. Stopping it causes uric acid levels to rise again, leading to more gout attacks. Talk to your doctor before stopping.
💬 Talk to your pharmacist or doctor for personalised advice about allopurinol.
Reviewed by a Registered Pharmacist NZ | BPharm, Pharmacy Council of New Zealand
References & Further Information
The following New Zealand and international resources were used to inform this page: