It works by suppressing (damping-down) the immune system. The aim of this medicine is to control inflammation and put the disease into remission.
Your child will not notice any immediate effects of taking azathioprine as it can take some weeks to start working. Most children take azathioprine for about two to three years. When your child has been in remission for a year or two, the dose will be gradually reduced and then stopped.
How is it given?
It is given by mouth, in the form of tablets or liquid, once a day.
Who should not take azathioprine?
People with the following conditions should discuss taking azathioprine with their doctor:
- Hypersensitivity to azathioprine or any of its ingredients.
- Hypersensitivity to mercaptopurine or any of its ingredients.
- Pregnant, could be pregnant, trying to become pregnant or breastfeeding.
What are the side effects?
Allergic reaction – some people receiving azathioprine have an allergic reaction to the drug. This reaction may be mild to severe. Signs of a mild allergic reaction include skin rashes and itching, high temperature, shivering, redness of the face, a feeling of dizziness or headache.
If you see any of these signs, please report them to a doctor or nurse. Signs of a severe allergic reaction include any of the above, as well as shortness of breath. If you are in hospital and your child shows signs of an 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 any of the following side effects are severe or carry on for a long time, please tell your doctor:
Alteration in blood count – azathioprine can affect your child’s blood, although this is rare. If your child has fewer red blood cells than normal, they could develop anaemia. Symptoms of anaemia include tiredness, lethargy and paleness. If your child has fewer white cells than normal, they could catch an infection more easily than usual. If your child has a lower number of platelets than usual, they could bruise easily. If you notice any unexplained bruising, bleeding, sore throat, temperature or other signs of infection, please contact your family doctor (GP) or local paediatrician for a blood test immediately.
Alteration in liver function – azathioprine can cause some mild changes to your child’s liver function. This should return to normal when your child stops taking the medicine. This will be monitored by regular blood tests.
Nausea and vomiting – these symptoms can be reduced by starting with a low dose of azathioprine and increasing it over time. Taking the medicine after meals can also help. Please tell your doctor if your child’s sickness is not controlled or persists.
Damage to the unborn baby – azathioprine must not be given to patients who may be pregnant or are likely to become pregnant in the near future. If your daughter is aged 10 years or older, we will ask her about her periods and any possibility that she could be pregnant. If your daughter is sexually active, she must use a reliable form of contraception.
Interactions with other medicines
Some medicines can react with azathioprine 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.
Keep medicines in a safe place where children cannot reach them.
Keep the azathioprine tablets at room temperature, away from bright light or direct sunlight and away from heat.
If your doctor decides that your child should stop taking azathioprine or the medicine passes its expiry date, please return it to your pharmacist. Do not flush it down the toilet or throw it away.
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.
Your child will need to have regular blood tests with your family doctor (GP) or local paediatrician. These blood tests check for the less common side effects mentioned previously. You will be given a card to record these results – please remember to bring it to your child’s clinic appointment.
Your child should NOT have any live vaccinations such as MMR, oral polio, chicken pox or BCG while taking azathioprine. Inactivated or killed vaccines such as influenza/flu, meningitis C, pneumococcal, hepatitis, Hib, tetanus, diphtheria, whooping cough/pertussis and the killed version of the polio immunisation are permitted if the patient is stable under treatment.
If your child is on azathioprine and has not had chicken pox but comes into contact with someone who has chicken pox or shingles (either face to face or longer than 15 minutes in the same room), you should report to your doctor immediately as your child may be at risk of developing a more severe form of the infection and may need special treatment with immunoglobulin. If your child gets chicken pox or shingles you should also report to your doctor immediately for aciclovir to be given.
If you are unsure whether your child has had chicken pox prior to starting azathioprine, their immunity should be checked with a simple blood test at that time and the result entered on the parent-held monitoring card.
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.