Allopurinol is a xanthine oxidase inhibitor medicine used to prevent build up of uric crystals in the body.
This build up can be caused by some illnesses or as a side effect of certain medicines. In adults, allopurinol can be used to prevent kidney stones and gout.
Allopurinol can be given at the start of a course of chemotherapy. When chemotherapy medicines start to kill the cancer cells, uric acid is released from these cells which can crystallise causing damage to the kidneys. Allopurinol stops these crystals from forming.
How is allopurinol given?
Allopurinol is given by mouth in tablet form. Allopurinol tablets should be taken after food with plenty of water.
What are the side effects of allopurinol?
Severe allergic reaction
Some people develop a severe allergic reaction to allopurinol. Signs of a severe allergic reaction include skin rashes and itching, high temperature, shivering, redness of the face, a feeling of dizziness or a headache, as well as shortness of breath or chest pain. If you are in hospital and your child shows signs of a severe allergic reaction, call a doctor or nurse immediately. If you are at home and your child shows signs of a severe allergic reaction, call an ambulance immediately. If your child has a severe reaction to allopurinol, the subsequent treatment will probably be changed.
If your child experiences the following side effects, please contact your doctor immediately as the dose may need to be reduced or stopped:
- Skin rash.
- Upset stomach, causing diarrhoea and/or constipation. Your child should continue to drink plenty of fluids and increase the amount of fibre eaten. Sometimes additional medicines may be prescribed to reduce these effects.
Allopurinol and interactions with other medicines
Some medicines can react with allopurinol, altering how well it works. Always check with your doctor or pharmacist before giving your child any other medicine, including medicines on prescription from your family doctor (GP), medicines bought from a pharmacy (chemist) or any herbal or complementary medicines.
Important information you should know about allopurinol
- Keep all medicines in a safe place where children cannot reach them.
- Allopurinol tablets should be kept in a cool, dry place away from direct sunlight or heat.
- If your doctor decides to stop treatment with allopurinol or the medicine passes its expiry date, return any remaining medicine to the pharmacist. Do not flush it down the toilet or throw it away.
- If your child vomits straight after taking the dose, inform your doctor or nurse, as your child may need to take another one.
If you forget to give your child a dose and it is within a few hours of when the dose was due, give it as soon as you remember. Otherwise, do not give this dose but wait until the next dose is due. Do not give a double dose.
Please read this information sheet from GOSH alongside the patient information leaflet (PIL) provided by the manufacturer. If you do not have a copy of the manufacturer’s patient information leaflet please talk to your pharmacist. A few products do not have a marketing authorisation (licence) as a medicine and therefore there is no PIL.
For children in particular, there may be conflicts of information between the manufacturer’s patient information leaflet (PIL) and guidance provided by GOSH and other healthcare providers. For example, some manufacturers may recommend, in the patient information leaflet, that a medicine is not given to children aged under 12 years. In most cases, this is because the manufacturer will recruit adults to clinical trials in the first instance and therefore the initial marketing authorisation (licence) only covers adults and older children.
For new medicines, the manufacturer then has to recruit children and newborns into trials (unless the medicine is not going to be used in children and newborns) and subsequently amend the PIL with the approved information. Older medicines may have been used effectively for many years in children without problems but the manufacturer has not been required to collect data and amend the licence. This does not mean that it is unsafe for children and young people to be prescribed such a medicine ‘off-licence/off-label’. However, if you are concerned about any conflicts of information, please discuss with your doctor, nurse or pharmacist.