About
Azathioprine is a medicine used to suppress the immune system. It belongs to a class of drugs called immunosuppressants. It works by reducing the activity of your immune system, which can help prevent your body from attacking itself in autoimmune diseases or rejecting transplanted organs.
Azathioprine is commonly prescribed for:
- Autoimmune diseases such as rheumatoid arthritis, lupus, or inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
- Preventing organ transplant rejection
- Certain blood disorders
Azathioprine is available in:
- Tablets (25 mg, 50 mg)
- Oral suspension (25 mg/mL)
How and When to Use It
Take azathioprine exactly as prescribed by your doctor.
Dosage: Usually taken once daily or in divided doses. Your dose depends on your condition, weight, and response to treatment.
Swallow tablets whole with water. If using a suspension, shake well before measuring the dose.
Do not stop taking azathioprine suddenly without consulting your doctor, as your condition may worsen.
Contraindications
Do not take azathioprine if you have:
- Allergy to azathioprine or related drugs (mercaptopurine)
- Severe liver disease or active liver inflammation
- Low blood cell counts (white cells, red cells, or platelets)
- Recent infections or uncontrolled infection risk
Side Effects
Like all medicines, azathioprine can cause side effects, although not everyone gets them.
Common side effects:
- Nausea or vomiting
- Loss of appetite
- Mild fatigue
- Rash
Serious side effects — seek medical attention immediately:
- Severe infections (fever, sore throat, persistent cough)
- Unusual bruising or bleeding
- Yellowing of skin or eyes (liver problems)
- Severe abdominal pain or persistent vomiting
Regular blood tests are usually needed to monitor blood counts and liver function during treatment.
Pregnancy, Breastfeeding & Fertility
Azathioprine should only be used in pregnancy or breastfeeding if clearly needed and prescribed by a doctor.
Discuss risks and benefits with your healthcare provider.
There is limited evidence on fertility, but no strong indication that azathioprine affects male or female fertility.
Interactions With Other Medications
Some medicines can affect how azathioprine works or increase the risk of side effects. Tell your doctor if you take:
- Allopurinol or febuxostat (gout medicines)
- Other immunosuppressants or chemotherapy drugs
- Live vaccines (may be less effective or unsafe)
- Certain antiviral or antifungal drugs
Frequently Asked Questions
What should I do if I miss a dose?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed one — do not double up.
Can I drink alcohol while taking azathioprine?
It’s best to limit alcohol, as it may increase the risk of liver problems.
Do I need regular blood tests?
Yes, regular monitoring of blood counts and liver function is essential while taking azathioprine.
How long will I need to take azathioprine?
The duration depends on your condition — it may be long-term for autoimmune diseases or transplant prevention. Follow your doctor’s guidance.
Can azathioprine increase my risk of infections?
Yes, because it suppresses your immune system. Avoid close contact with sick people and report any signs of infection promptly.
Medical Disclaimer: This information is provided for educational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a healthcare professional before starting, stopping, or changing any medication.
Last reviewed: June 2026
