Allopurinol – Xanthine oxidase inhibitor for gout prevention and uric acid control.
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What is Allopurinol?
Allopurinol is the gold standard medication for preventing gout attacks and managing chronic hyperuricemia. By blocking uric acid production at its source, it provides effective long-term management of gout while also protecting against kidney stones and kidney damage from high uric acid levels.
Book an online consultation if you’re experiencing recurrent gout attacks, have been diagnosed with high uric acid levels, develop kidney stones, or need assessment for gout prevention. Our GPs can evaluate your uric acid levels and determine if Allopurinol or other gout treatments are appropriate for your specific condition.
What is Allopurinol used for?
- Gout prevention
- Chronic hyperuricemia (high uric acid)
- Kidney stone prevention (uric acid stones)
- Tumor lysis syndrome prevention
- Secondary hyperuricemia from medications
- Chronic kidney disease with hyperuricemia
- Recurrent gout attacks
How does Allopurinol work?
Inhibits xanthine oxidase, the enzyme responsible for converting purines to uric acid, thereby reducing uric acid production and preventing the formation of uric acid crystals that cause gout attacks and kidney stones.
Dosage and Administration
Adults
Starting dose: 100mg once daily. Gradually increase by 100mg every 2-4 weeks until uric acid target reached. Usual maintenance: 200-600mg daily.
Children
Rarely used in children—specialist supervision required for specific conditions like tumor lysis syndrome.
Important Notes
- Take after food to reduce stomach upset.
- Start with low dose to minimize risk of precipitating gout attack.
- May need colchicine or NSAID cover for first 3-6 months.
- Regular monitoring of uric acid levels and kidney function required.
Side Effects
Common Side Effects
- Skin rash
- Stomach upset and nausea
- Drowsiness
- Headache
- Metallic taste
- Initial worsening of gout (first few months)
Serious Side Effects
Seek immediate medical attention if you experience:
- Severe skin reactions (Stevens-Johnson syndrome)
- Allopurinol hypersensitivity syndrome
- Severe allergic reactions
- Blood disorders
- Liver problems
- Kidney problems
Important Warnings
- Tell your GP immediately if you develop skin rash—can be sign of serious reaction.
- May initially worsen gout attacks—often prescribed with colchicine for first 3-6 months.
- Regular blood tests needed to monitor uric acid, kidney, and liver function.
- Don't stop suddenly during gout attack—may worsen symptoms.
- Tell your GP if you have kidney problems—dose adjustment needed.
Drug Interactions
Tell your GP if you're taking any of the following medications:
- Azathioprine and mercaptopurine—dangerous interaction, requires dose reduction.
- Warfarin—may enhance anticoagulant effects.
- ACE inhibitors—increased risk of allergic reactions.
- Theophylline—may increase theophylline levels.
- Ciclosporin—may increase ciclosporin levels.
Frequently Asked Questions
Why does Allopurinol sometimes make gout worse initially?
As uric acid levels drop, existing crystals in joints can shift and trigger attacks. This usually settles after 3-6 months. Your GP may prescribe colchicine to prevent this.
How long does it take for Allopurinol to prevent gout attacks?
It typically takes 6-12 months of consistent use to significantly reduce gout attack frequency, as existing uric acid deposits slowly dissolve.
What uric acid level should I aim for?
Generally below 360 micromol/L (6mg/dL), though your GP may aim lower if you have frequent attacks or kidney problems.
Can I stop Allopurinol once my gout is better?
No, stopping allopurinol will cause uric acid levels to rise again and gout attacks to return. It's typically a lifelong treatment for chronic gout.
Medically Reviewed by: Mohammed Hassan - Independent Prescriber
Last Updated: 2025-01-14