Allopurinol for hyperuricaemia

This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults. Read this leaflet carefully. Keep it somewhere safe so that you can read it again.

Name of medicine


Brand names: Caplenal, Cosuric, Rimapurinol, Zyloric

Why is it important for my child to take Allopurinol?

Your child needs to take allopurinol to stop the body making too much uric acid. Uric acid is made in the body when food is digested and when cells are broken down naturally. Too much uric acid in the blood is called hyperuricaemia, and it can lead to crystals being formed. This can cause gout and make the kidneys work less well. Your child should drink plenty of liquid each day (4 or 5 large glasses of water) to help this.

Gout is a type of arthritis, it happens when the crystals form inside joints. The most common symptom is sudden and severe pain in the joint, along with swelling and redness. The joint of the big toe is the joint usually affected, but it can develop in any joint.

What is Allopurinol available as?

  • Tablet: 100 mg, 300 mg; these contain small amounts of lactose
  • Liquid medicine can be ordered specially from your pharmacist: 100 mg in 5 mL

When should I give Allopurinol

Allopurinol can be given once or twice each day.

  • Once a day: it can be given in the morning or the evening.
  • Twice a day: give once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example some time between 7am and 8am, and between 7pm and 8pm.

Give the medicine at about the same time(s) each day so that this becomes part of your child’s daily routine, which will help you to remember.

How much should I give?

Your doctor will work out the amount of Allopurinol (the dose) that is right for your child. The dose will be shown on the medicine label.

It is important that you follow your doctor’s instructions about how much to give.

How should I give Allopurinol?


  • Tablets should be swallowed with a glass of water, squash or juice. Your child should not chew the tablet.

Liquid medicine

  • Shake the medicine well. Measure out the right amount using an oral syringe or a medicine spoon. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount.

When should the medicine start working?

Allopurinol will lower the amount of uric acid in your child’s blood within a few weeks. You may not notice much difference in your child but their kidneys will be protected from damage. If your child has gout, the attacks may continue for a few months until all the crystals of uric acid in the tissues have dissolved away. Continue to give the medicine to your child during this time. If you are worried about whether it is helping, contact your doctor.

What if my child is sick (vomits)?

  • If your child is sick less than 30 minutes after having a dose of Allopurinol, give them the same dose again.
  • If your child is sick more than 30 minutes after having a dose of Allopurinol, do not give them another dose. Wait until the next normal dose.

If your child is sick again, seek advice from your family doctor, nurse, pharmacist, or hospital. They will decide what to do based on your child’s condition and the specific medicine involved.

What if I forget to give it?

If you usually give it twice a day: If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7am, you can give the missed dose at any time up to 11am. If you remember after that time, do not give the missed dose. Give the next dose as usual.

If you usually give it once a day in the morning: Give the missed dose when you remember during the day, as long as this is at least 12 hours before the next dose is due.

If you usually give it once a day in the evening: If you remember before bedtime, give the missed dose. You do not need to wake a sleeping child to give a missed dose. You can give the missed dose in the morning, as long as this is at least 12 hours before the evening dose is due.

What if I give too much?

You are unlikely to cause harm if you give an extra dose of Allopurinol by mistake. If you are concerned that you may have given too much, contact your doctor or local NHS services (details at end of leaflet). Have the medicine or packaging with you if you telephone for advice.

Side effects you must do something about

If your child is short of breath or is wheezing, or their face, lips or tongue start to swell, or they develop a rash, they may be allergic to Allopurinol. Take your child to hospital or phone for an ambulance straight away.

If your child seems to bruise more easily or bleeding doesn’t stop as quickly as usual, or if their skin or whites of the eyes get a yellow tinge, contact your doctor straight away, as there may be a problem with your child’s blood or liver.

If your child gets a skin rash, stop giving the medicine and contact your doctor straight away. They may want to stop the medicine and start it again gradually. This can happen months or years after treatment is started.

Other side-effects you need to know about

  • Your child’s hair may become thinner and some may fall out. It should grow back when the medicine is stopped. If this happens, discuss it with your doctor at your next visit.

These effects should wear off as your child gets used to the medicine. If you are worried or they are still a problem after two weeks contact your doctor:

  • Your child may get pins and needles.
  • Your child may say that things taste different.
  • They may get headaches, feel sleepy, have blurred eyesight or red eyes.
  • Your child may get stomach pain or cramps, and may feel sick (nausea) or be sick (vomit). Giving the medicine with some food or milk may help. These side effects usually wear off after a few days as your child gets used to the medicine. If they are still a problem after one week contact your doctor.

  • Your child’s hair may become thinner and some may fall out. It should grow back when the medicine is stopped. Discuss this with your doctor at your next visit.

  • Your child may feel dizzy or light-headed when they stand up. Encourage them to sit down for a short time after taking the medicine and to stand up slowly and to sit or lie down if they feel dizzy or light-headed.

Can other medicines be given at the same time as Allopurinol?

  • You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
  • Allopurinol should not be taken with some medicines. Tell your doctor or pharmacist about any other medicines your child is taking before giving Allopurinol.

Is there anything else I need to know about this medicine?

  • It is important to make sure your child drinks plenty of liquid each day (4 or 5 large glasses of water).
  • Your doctor will check your child’s blood from time to time, to make sure the treatment is working

General advice about medicines

  • Try to give medicines at about the same times each day, to help you remember.
  • If you are not sure a medicine is working, contact your doctor but continue to give the medicine as usual in the meantime. Do not give extra doses, as you may do harm.
  • Only give this medicine to your child. Never give it to anyone else, even if their condition appears to be the same, as this could do harm.
  • If you think someone else may have taken the medicine by accident, contact your doctor for advice.
  • Make sure that you always have enough medicine. Order a new prescription at least 2 weeks before you will run out.
  • Make sure that the medicines you have at home have not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.

Where should I keep this medicine?

  • Keep the medicine in a cupboard, away from heat and direct sunlight.
  • You may need to keep liquid medicine in the fridge – check the instructions on the bottle. Make sure the medicine does not freeze.
  • Keep the medicine in the container it came in.
  • Make sure that children cannot see or reach the medicine.

Who to contact for more information?

Your doctor, pharmacist or nurse will be able to give you more information about Allopurinol and about other medicines used to treat hyperuricaemia.

England: NHS 111

Tel 111

Scotland: NHS 24

Northern Ireland: NI Direct

Wales: NHS Direct

Tel 111 (free) or 0845 46 47 (2p per minute)

Copyright disclaimer

Version [1]. © NPPG, RCPCH and WellChild, all rights reserved. Review by November 2015.

The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website,

We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.