azathioprine at a glance
Medicine class
Immunosuppressant antimetabolite
Main roles
Preventing transplant rejection and controlling selected autoimmune or inflammatory conditions
Onset
Benefits develop gradually and may take weeks or months to appear
Monitoring
Regular blood counts and liver and kidney checks are required
Food and milk
Take consistently in relation to food and do not take with milk or dairy products
What is azathioprine used for?
Selected UK products license azathioprine for:
Preventing rejection after specified solid-organ transplants, alongside other immunosuppressive treatment
Moderate to severe Crohn’s disease or ulcerative colitis when corticosteroids are needed, unsuitable or insufficient
Selected severe autoimmune and inflammatory disorders, including rheumatoid arthritis, systemic lupus erythematosus, autoimmune hepatitis, inflammatory muscle disease and polyarteritis nodosa
Selected severe skin disorders, including pemphigus; the oral suspension also includes bullous pemphigoid and Behçet’s disease
Refractory autoimmune haemolytic anaemia and immune thrombocytopenic purpura
For the oral suspension: relapsing multiple sclerosis in adults and generalised myasthenia gravis
How does azathioprine work?
Azathioprine is converted to mercaptopurine and then to active thiopurine nucleotides. These interfere with purine metabolism and production of rapidly dividing immune cells, reducing damaging immune responses and helping protect transplanted organs.
azathioprine preparations and strengths
Oral suspension
Route: Oral
Strengths: 10 mg/mL
Tablet
Route: Oral
Strengths: 25 mg, 50 mg
How to take azathioprine
Follow the product-specific instructions and use the same relationship to food each time.
Swallow tablets whole with water. Taking them after food may reduce nausea, but do not take them with milk or dairy products.
Shake the oral suspension thoroughly before measuring it. Use the supplied oral syringe selected by the healthcare professional and drink water afterwards.
Caregivers handling the suspension should wash their hands and use disposable gloves. Avoid skin or mucosal contact and clean spills immediately.
azathioprine side effects
Common or expected effects
- Nausea; vomiting is also common with the oral suspension
- Reduced white blood cells or broader bone-marrow suppression
- Reduced platelet count
Get urgent medical advice
- Serious or unusual infections
- Severe bone-marrow suppression causing fever, bleeding, bruising or marked weakness
- Liver injury or cholestasis, including jaundice or severe itching
- Pancreatitis, typically causing severe abdominal pain
- Severe hypersensitivity or serious blistering skin reactions
- Rare neurological symptoms such as seizures, confusion, severe headache or visual disturbance
azathioprine in pregnancy
Azathioprine can be used during pregnancy when a specialist judges that disease or transplant control outweighs potential risks; do not stop it without advice. Current UK pregnancy information finds no good evidence that it harms the baby, although maternal blood and liver monitoring is important.
azathioprine while breastfeeding
UK patient guidance states that azathioprine may be used while breastfeeding a healthy baby following professional advice because milk transfer is small. Product licences differ: the selected tablet advises avoiding breastfeeding unless benefits outweigh risks, while Jayempi lists breastfeeding as contraindicated. Seek formulation-specific specialist advice.
azathioprine interactions
Check all prescribed, over-the-counter and complementary products with a pharmacist or prescriber.
Allopurinol, oxipurinol or thiopurinol
These strongly reduce azathioprine breakdown, creating a potentially severe toxicity risk requiring specialist adjustment and close monitoring.
Febuxostat
It may substantially increase azathioprine exposure and bone-marrow toxicity; combined use is not recommended in the selected product information.
Ribavirin
It can reduce azathioprine efficacy while increasing severe bone-marrow toxicity, so combined use is not advised.
Common questions about azathioprine
Answers are fully visible for fast scanning and source review.
How long does azathioprine take to work?
Improvement may begin after several weeks, but full benefit can take months and may not produce an obvious sensation after transplantation.
Why are blood tests needed?
Azathioprine can suppress bone marrow and affect the liver or kidneys. Tests help detect toxicity before it causes serious symptoms.
Can azathioprine be taken with food?
Tablets may be taken with or without food, but the approach should be consistent; food may help nausea. Jayempi is taken away from meals according to its product instructions.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.