Medication Information Leaflet

What is this medication for?

Allopurinol is used to prevent gout, a condition that can cause pain and swelling in the joints. 
Gout happens when there is too much uric acid in the blood. Uric acid is a chemical that is produced when the body breaks down certain food.  Allopurinol reduces the production of uric acid, thus lowering the uric acid levels in the body.

Allopurinol is also used in the treatment of uric acid stones and to prevent uric acid levels from going up too high during chemotherapy.

How should I take/use this medication?

  • Do not stop taking your medication without checking with your healthcare professional.
  • This medication should be taken with or after food to reduce stomach upset. 
  • Take this medication with plenty of water. 

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose. 

What precautions should I take?

Inform your healthcare professional if: 
  • You are allergic to this medication or any of the other ingredients of this medication
  • You have history of kidney condition
  • You are pregnant, planning to become pregnant, or breastfeeding 
  • You are taking any other medications, including supplements, traditional medications and herbal remedies. 

It may take a few weeks before you get the full benefits from taking this medication.

Drink enough water (2-3 litres of water a day) unless your doctor has advised you to restrict fluid intake.

Follow the diet plan recommended by your doctor or dietician.

What are some common side-effects of this medication?

  • Diarrhea
  • Upset stomach
    • Take this medication with or after food to reduce stomach upset

When allopurinol is started for gout prevention, the chances of having gout attacks may be higher initially. Do not stop taking this medication without checking with your doctor. Your doctor may prescribe another medication to be taken together to reduce the risk of getting gout attacks during the initial period of this medication. 

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 
  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body
Very rarely, a bad skin reaction known as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TENs) may happen. This can cause serious health problems that may sometimes be life threatening. Stop this medication and see a doctor immediately if you have signs like face swelling, blisters or peeling on skin, skin rashes that spread within hours to days.

Very rarely, this medication may also injure or damage the liver. A liver injury may recover on its own. However, in some cases, it may cause serious liver damage. Stop this medication and see a doctor immediately if you notice any dark-coloured urine, light coloured stools, yellowing of skin or eyes.

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately. 

What food or medication should I avoid when I take this medication?

Inform your doctor if you are taking:
  • Warfarin
  • Azathioprine
  • Mercaptopurine

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How should I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Sept 2021

Back to Top