Azathioprine / Imuran
Content date: 11 November 2026
An immune-modifying medicine used in selected cases of Crohn’s disease, ulcerative colitis, autoimmune hepatitis and after transplantation. Benefit takes weeks to months; it is not a rapid treatment for an acute flare.
Your next step
Check your written prescription and monitoring plan. If anything is unclear, ask your care team before changing a dose.
Get urgent help: Severe persistent abdominal pain, especially with vomiting, breathing difficulty, or fever with severe illness: seek urgent assessment.
How do I use it?
- Follow the dose calculated from your weight and tests. It is usually taken daily; doses may be divided when prescribed. Swallow tablets whole. Do not take with milk or dairy; follow the spacing instructions in your own leaflet. Never double a missed dose or adjust the dose yourself.
How do I store it?
- Keep in the original packaging away from children. Follow your pack’s temperature and light instructions; avoid a hot car. Ask the pharmacist if swallowing is difficult rather than crushing tablets yourself.
What tests do I need?
- Blood counts and liver/kidney tests are checked before treatment, frequently after starting or dose changes, and regularly afterwards. TPMT testing helps estimate the risk of certain side effects and guide dosing; NUDT15 may also be checked depending on your situation. These checks never replace regular blood counts, even when symptoms improve.
Possible side effects: what to expect
- Not everyone experiences side effects. Nausea may occur, particularly initially. Ask your pharmacist about food and dose timing for your product; your team can adjust how it is taken if needed. Do not split doses or stop it yourself.
- Blood-cell reductions, liver problems or infections can occur; regular tests help detect problems early. Pancreatitis can also occur, so persistent severe pain needs urgent assessment. Longer-term cancer risks are discussed individually, alongside sun protection and appropriate screening.
Important points
- Disclose all medicines: allopurinol requires a specialist dose-adjustment plan, and febuxostat is usually avoided. Discuss vaccines, pregnancy and breastfeeding. Do not automatically stop treatment if pregnancy occurs.
Brand / device: ........................ | Dose and how I take or use the medicine: ........................
Next dose: ........................ | Next blood tests: ........................
Team contact: ........................
When to get help
Severe persistent abdominal pain, especially with vomiting, breathing difficulty, or fever with severe illness: seek urgent assessment.
Fever, sore throat, mouth ulcers, unusual bruising or yellow eyes: contact the team the same day to review tests and the next dose. During pregnancy, report new intense itching without a rash to your maternity and treating teams the same day, even without jaundice; you may need liver and bile-acid tests and a treatment review.
Related guides
Pregnancy and breastfeeding with bowel and liver disease
Anti-rejection medicines after liver transplantation: a practical guide