Bone & metabolism
Allopurinol
Urate-lowering therapy — The first-line drug to prevent gout attacks by lowering uric acid.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Allopurinol is the standard long-term treatment to prevent recurrent gout and uric-acid kidney stones by lowering uric-acid levels. It is preventive, not a treatment for the acute attack.
How it works
It inhibits xanthine oxidase, the enzyme that produces uric acid, lowering urate so that crystals dissolve over time and stop forming in joints.
In practice
In practice the common mistakes are starting allopurinol during an acute attack (it can worsen it) and starting too high. Begin once the flare has settled, start low and titrate to a target urate, and cover the early months with an anti-inflammatory or colchicine because urate-lowering can transiently trigger attacks. Adjust in renal impairment, and be alert to the rare but serious hypersensitivity reaction, which is more common in certain groups.
Examples
Practical use
How to take it & use it well
- Take this tablet once daily, usually after food to reduce the chance of stomach upset.
- Drink plenty of fluids through the day while taking it.
- Keep taking it every day for the long term, as it prevents future gout attacks rather than treating one happening now.
- Do not stop it during a gout attack; carry on at your usual dose and treat the flare with the medicines your prescriber recommends.
- Expect that flares may briefly become more likely when first starting, which is normal as uric acid levels readjust.
Common uses
- Prevention of recurrent gout
- Uric-acid kidney stones
- Prevention of high urate in some cancer treatment (specialist)
Monitoring
- Urate level titrated to target
- Renal function
- For rash or hypersensitivity early in treatment
Weighing it up
Advantages & disadvantages
Advantages
- Taken regularly it lowers uric acid and reduces how often painful gout attacks happen.
- Over time it can shrink the uric acid deposits known as tophi.
- It is a once-daily tablet that is straightforward to take.
- It can help protect the kidneys and joints from long-term damage caused by high uric acid.
Disadvantages
- Gout flares can increase in the first weeks of treatment before the medicine settles things down.
- It can rarely cause a serious skin reaction, so any spreading rash needs urgent attention.
- It does not relieve the pain of an attack that is already happening.
- It usually needs to be taken indefinitely to keep working, which means a lifelong daily habit.
Key safety principles
What to watch for
- Do not start during an acute attack; cover the first months against flares.
- Rare but serious hypersensitivity/skin reactions — stop and seek help if a rash develops.
- Reduce dose in renal impairment; interacts with azathioprine.
Key interactions
What to avoid or check alongside
- With azathioprine or mercaptopurine it can cause dangerous build-up of these drugs and severe blood problems, so the combination needs specialist care.
- It can increase the effect of warfarin, raising bleeding risk and the need for clotting checks.
- Taken with ACE inhibitors or some water tablets, the risk of allergic and skin reactions may rise.
- It can raise levels of theophylline, increasing side effects such as a fast heartbeat.
Patient & carer advice
- Keep taking it during a gout attack once established, but expect it to be started only when the attack has settled
- Stop and seek urgent advice if you develop a rash
- It works long-term — do not stop when attacks settle
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
Allopurinol: frequently asked questions
Does allopurinol treat a gout attack?
No. It is a preventer that lowers uric acid over time. An attack already underway is treated with anti-inflammatory or other flare medicines, while allopurinol is continued.
Should I stop allopurinol during a flare?
No. Stopping and restarting can trigger more attacks. Keep taking your usual dose and treat the flare separately with the medicines your prescriber advises.
Why am I getting more gout after starting allopurinol?
Flares can briefly increase when treatment starts because uric acid levels are shifting. This usually settles, and your prescriber may give cover to reduce flares early on.
How long do I need to take allopurinol?
Usually long term, often for life, because uric acid rises again if it is stopped. Regular use keeps levels low and prevents attacks.
What rash should I worry about on allopurinol?
Any new or spreading rash, especially with fever, blistering or mouth sores, should be treated as an emergency. Stop the tablet and seek urgent medical help.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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