Allopurinol: Uses, Side Effects, and How to Take It
Allopurinol is a prescription medicine that lowers uric acid in the blood. It is used to prevent gout attacks, treat high uric acid, and reduce the risk of uric acid kidney stones.
Allopurinol can help prevent gout when taken consistently, but starting treatment may initially trigger more attacks. Take it only as prescribed and report new rashes or other concerning symptoms promptly.
Key facts at a glance
- ATC
- M04AA01
- Generic
- Allopurinol
- Class
- antigout
- Brands
- Zyloprim, Aloprim
- Availability
- rx
- Pregnancy
- C
- Lactation
- caution
- Half-life (h)
- 2
- Duration (h)
- 24
- Routes
- oral, iv
- Forms
- tablet, injection
- Regions
- CN, US, EU, JP
- Monitoring
- liver-function, renal-function, rash
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
11 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks. Consider alternative gout management
regular fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
second trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks
regular fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
third trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks. Consider alternative therapies
regular fetal monitoring and uterine activity
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedinguse with caution or avoid
allopurinol and its metabolite oxypurinol are excreted in breast milk. Consider avoiding breastfeeding or discontinue drug
monitor infant for adverse effects
Use with caution and monitor for adverse effects.
geriatric
elderlyreduce starting dose, monitor renal function
start at lower doses due to age-related decline in renal function. Adjust dose based on renal function
monitor renal function and uric acid levels regularly
Use with caution and monitor for adverse effects.
pediatric_age
childrendose based on body surface area
used for hyperuricemia associated with chemotherapy, Lesch-Nyhan syndrome. Dose is typically 10-20mg/kg/day
monitor uric acid levels, renal and hepatic function
Use with caution and monitor for adverse effects.
renal_impairment
mildreduce dose to 200mg daily
monitor renal function. May adjust dose based on serum uric acid levels
monitor renal function and uric acid levels
Use with caution and monitor for adverse effects.
renal_impairment
moderatereduce dose to 100-200mg daily
significant dose reduction required. Consider alternative if creatinine clearance <30 mL/min
close monitoring of renal function and uric acid levels
Use with caution and monitor for adverse effects.
renal_impairment
severereduce dose to 100mg daily or less, consider alternate day dosing
use with extreme caution. Consider alternative urate-lowering therapy
frequent monitoring of renal function, uric acid, and oxypurinol levels if available
Use with caution and monitor for adverse effects.
hepatic_impairment
mild to moderateno specific adjustment, use with caution
use with caution. Monitor liver function tests
monitor hepatic function periodically
Use with caution and monitor for adverse effects.
alcohol_users
activeno specific adjustment
limit alcohol consumption as it can increase uric acid levels and reduce drug efficacy
monitor uric acid levels more frequently
Use with caution and monitor for adverse effects.
Statistics and clinical data
FDA approval year
Original FDA approval for gout treatment
Drug class
Pharmacological classification
Primary indications
Main therapeutic uses
Mechanism of action
Pharmacodynamic properties
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 22, 2026. · Read our editorial policy