Pharmacy - Azathioprine

Why have I been prescribed azathioprine?

Azathioprine is a medication that can be used to manage auto immune conditions. It is used in several specialties including renal, dermatology, rheumatology and neurology. It is also used as an anti-rejection medicine after organ transplantation to stop the body rejecting the transplant. The clinical team that prescribes this medicine for you will tell you about your condition and why azathioprine is being prescribed.

How does it work?

Azathioprine belongs to a group of medicines known as immunosuppressants. It helps to reduce or suppress your body’s own immune system (your immune system helps to protect you against infections). However, sometimes it can overreact or react abnormally and cause illness. Azathioprine can be used to treat these conditions, often in combination with other medicines

Azathioprine works slowly and may take several weeks to take effect.

What dose do I take?

The dose of azathioprine depends on your weight and the medical condition being treated. Typical doses vary between 25mg to 200mg once a day.

Before you start you will have a blood test done (thiopurine methyltransferase – TPMT). This assesses the level of a particular enzyme in your blood. Enzymes are proteins in your body that can help to break down certain substances or chemicals. TPMT helps to breakdown and remove azathioprine from your body. If you have a low level of the enzyme, then you will be on a lower dose of azathioprine compared to someone with higher levels to help reduce the risk of side effects. If your TPMY result is very low, azathioprine may not be the right medication for you.

How do I take azathioprine?

Azathioprine is available as 25mg and 50mg tablets. You should always take the medicines as directed by the prescriber.

It is usually taken once daily but can be split into two doses if you prefer.

This is a long-term treatment which you may be on for several years.

You should take azathioprine with or immediately after food to help reduce stomach upsets.

Do not cut the tablets in half as this can create small amounts of dust that could cause side effects to you and those around you.

Does azathioprine interfere with my other medicines?

Azathioprine can interact with other medicines. You should tell your doctor which medicines you are taking before starting azathioprine.

Your regular prescription medicines will be checked against azathioprine, and any changes will be made if needed. If you buy any medication from the chemist such as 'over the counter' or herbal medicines, for example, you must talk to your pharmacist before taking them, as some medicines can affect how azathioprine works.

• Do not take allopurinol (a medicine used to prevent gout) without discussing with your doctor first
• Other medicines which interact with azathioprine include co- trimoxazole, trimethoprim and warfarin. Please let your doctor know if you take any of these medicines
• Always check with your doctor or pharmacist first before starting any new medication
• You should avoid ‘live’ vaccines but most travel vaccines and the ’flu jab are ok (see below)
• It is safe to drink alcohol in moderation while taking azathioprine, but it may make nausea worse

Can azathioprine cause side effects?

Azathioprine acts on the white cells of your immune system so it is important to know the signs that the white cells are too low. You should seek medical attention if you have any of the following:

• Sore throat
• Fever
• Feeling generally unwell
• Unexpected bruising or bleeding

Please also contact the team if you notice any yellowing of the eyes or unexpected bruising or bleeding as this may indicate issues with your liver.

The most common side effects are:

• Generally, not feeling quite yourself, including some dizziness and aches and pains
• Stomach upsets, such as feeling sick or diarrhoea
• Rash
• Bruising
• Hair loss, although hair often starts to grow again

These symptoms can often be worse at the start of treatment and will hopefully settle after a few days or weeks. However, it is important to remember these side effects as they can happen if you have been taking azathioprine for several years, not just at the start of treatment.

Azathioprine can affect the liver; a small number of patients can have abnormal liver function blood test results. Usually this happens in the first month of starting azathioprine. Patients don’t usually have any symptoms and blood test results usually return to normal by themselves or by reducing the dose of the medication.

In the long-term there is a higher risk of cancers compared with the general population. We recommend that you use avoid excessive exposure to sunlight by wearing long sleeves, long trousers and a sun hat, not sunbathing and using high factor sun cream, of at least SPF 30 even in winter. This will help to reduce skin damage. Regular surveillance, such as cervical screening (smear tests) and mammograms when eligible are recommended for women.

Please highlight to your healthcare professional if you notice any changes to your skin or sudden unexpected weight loss.

Contact your healthcare team if you get chickenpox or shingles, or if you come into contact with someone who has them and you’ve never had chickenpox before. These illnesses can be worse than usual if you’re on azathioprine. You may need treatment for them, and your azathioprine may be stopped until you’re better.

What happens if I forget to take a dose?

If you remember within 12 hours of your dose being due, then take your dose as usual. If it is more than 12 hours since your dose was due, do not take the dose and take your next dose at the normal time.

Never double up on doses. If you have missed more than one dose, or are not sure what to do, contact your medical team for advice. If you have diarrhoea or vomiting for 48 hours (2 days), you might not be absorbing enough of the drug to work properly, so you must contact your medical team.

Can I have a family while I'm taking azathioprine?

If you are planning to become pregnant while you are taking azathioprine, you should discuss this with your doctor. Current guidelines say that azathioprine can be taken when pregnant or breastfeeding. It is safe for men to continue taking azathioprine when trying for a baby.

Do I need any special checks while on azathioprine?

Yes. At first, you will need to have regular blood tests to check your kidney function, liver function and full blood count at the start of treatment. The frequency of these tests will be reduced as your treatment carries on. Your prescriber will tell you how often these tests will be, but they are usually every 2-4 weeks for the first 3-4 months, then will reduce in frequency.

Can I drink alcohol while taking azathioprine?

Because azathioprine can affect the liver, you should ensure you don’t drink large amounts of alcohol whilst taking this medication. Don’t drink more than 14 units of alcohol each week and have at least two alcohol-free days a week. You can get more information about alcohol, units of alcohol and help and support at:
https://www.nhs.uk/live-well/alcohol-support/calculating-alcohol- units/

Can I travel while taking azathioprine?

If you are planning on travelling whilst taking azathioprine, it is important to discuss this with the specialist clinic. Keep in mind the following advice:

• Always take extra supplies of your medication when travelling
• Keep your medication in your hand luggage
• Carry your medication in their original boxes
• If you’re travelling to a different time zone, try to take your medication at your usual 'native' time. If this is difficult, discuss with your clinician in the clinic

In many parts of the world there is a greater risk of developing an infection. To help avoid picking up these infections you must:

• Wash your hands thoroughly, especially after using public toilets
• Use alcohol hand gel: you can buy this from most supermarkets and chemists to take with you
• Follow the advice below on food and water safety:
  –    Don’t drink tap water or use it to brush your teeth. Use bottled water instead
  –    Don’t put ice in drinks
  –    Bottled fizzy drinks with an unbroken seal are usually safe
  –    Boiled water and drinks made with boiled water are usually safe
  –    Don’t eat salads, raw (uncooked) fruits and vegetables, unless you have washed and peeled them yourself
  –    Don’t eat food that has been kept at room temperature in warm places or that could have been exposed to flies 
  –    Don’t eat or drink unpasteurised milk, cheese, ice cream or other dairy products
  –    Don’t eat raw or undercooked seafood

Can I have vaccinations while taking azathioprine?

Whilst taking azathioprine, you must not have any live vaccines. Your immune system is dampened down whilst taking azathioprine, which increases your risk of infection. Other types of vaccines are safe for you to have. Ensure you discuss any vaccinations you need with the clinic.

We strongly advise that all patients who have a reduced immune system have the flu vaccination each year and follow the recommended COVID vaccination schedule – your clinical team will advise you. If your GP or Practice Nurse needs advice about vaccinations, they can contact the clinic.

Tips to reduce your risk of infection

• Try to avoid close contact with people you know have an active infection
• Wash your hands regularly and carry round a small bottle of antibacterial gel to use
• Keep your mouth clean by brushing your teeth regularly
• Make sure your food is stored and prepared properly
• Try to keep your house clean and hygienic, especially the kitchen, bathrooms and toilets
• Have your annual vaccines are up to date

Contact details

Renal Outpatients 0161 206 1478