Drug Name

Brand Name(s)
Zyloprim®, generics

Drug Class
Prescription medication

Allopurinol is used to lower uric acid in the blood, to prevent attacks of gout

Allopurinol is not used to treat inflammatory arthritis or osteoarthritis.

  • How is allopurinol administered?

    Allopurinol is taken orally in pill form.

  • What is the typical dose and when do I take it?

    Allopurinol is available in 100, 200 and 300 mg tablets.

    The usual dose is between 100 – 600 mg taken once daily (Maximum dose: 800 mg/day)

    If you have poor renal function you may need a lower daily dose. Please discuss this with your healthcare provider.

  • How long will it take to work?

    Be patient, you will not feel the effects of allopurinol right away. It may take a few weeks to feel the effects of allopurinol. The chance of gout attacks may be higher for a few months after your start taking this medication. It is important to keep taking the medication unless told otherwise by a healthcare professional.

    To provide symptom relief while you are waiting for allopurinol to work and to protect against gout flares, your prescriber may recommend you take a non-steroidal anti-inflammatory drug (NSAID) or colchicine.

  • When should I not take allopurinol and call my doctor? (concern/action)

    Allopurinol should not be started new during an acute gout attack as it may make the attack worse.

    Allopurinol has not been well studied in pregnancy. Human data suggests that risks may be low and that allopurinol may be safe, but before starting allopurinol tell your healthcare provider if you are pregnant or planning to become pregnant.

    Allopurinol does pass into breast milk. Allopurinol is likely safe in breast feeding although human data is limited. Allopurinol is considered by the American Academy of Pediatrics to be compatible with breastfeeding. Breastfed infants of mothers receiving allopurinol should be monitored for signs of allopurinol side effects, such as rash. Infants whose mothers require treatment with allopurinol may also require periodic blood work.

    Allopurinol interacts with a number of other medications. Please speak with your healthcare provider about whether any of the other medications you currently take interact with allopurinol.

    Anyone who is hypersensitive to allopurinol or has had a previous allergic reaction to allopurinol should avoid the medication.

  • What are the side effects of allopurinol?

    A common side effect of allopurinol is rash. Sometimes people can develop a more serious type of rash while taking allopurinol. If you develop a rash while taking allopurinol stop the medication and contact your healthcare provider.

    Other common side effects include stomach upset and diarrhea.

    A rare, but serious side effect of allopurinol is that the medication can cause an allergic reaction. Symptoms include fever, chills, nausea, vomiting, joint pain, and skin rash. If you develop any of these symptoms stop the medication and contact your healthcare provider. Your risk of this reaction may be increased if you have decreased kidney function or if you take certain medications. Talk to your prescriber about your kidney function and the other medications you take before starting allopurinol.

  • What helps to reduce side effects?

    Take your allopurinol as prescribed and contact your health-care provider if you have any concerns while taking the medication.

    To reduce stomach issues take allopurinol with food or after a meal.

    Drinking alcohol can flare your gout. It is best to avoid alcohol if you have gout.

  • Do I need any monitoring while taking allopurinol?

    Blood tests may be required every 3 – 6 months while you are talking allopurinol. This will help check your blood counts, liver/kidney function and follow the activity of your gout.

This information was last updated November 2017, with expert advice from:

Jason Kielly, B.Sc. (pharm.), Pharm.D.
Assistant Professor, School of Pharmacy, Memorial University of Newfoundland
Clinical Pharmacist, Rheumatic Health Program, Eastern Health

Go Back to Drug Index