Imuran (azathioprine)
How this therapy is used at Arthritis Care of Texas in Corpus Christi, TX — what it is, how it is taken, side effects, and safety checks.
- Treats
- Lupus (SLE) · Rheumatoid arthritis · Polymyositis · Dermatomyositis
- How given
- Pill
- How often
- Once or twice daily
Imuran is a disease-controlling treatment: it calms the immune system to control inflammation in lupus, vasculitis, and inflammatory arthritis and to protect organs from damage. It works slowly — judge it over 2–3 months — and it is not a painkiller. Its benefit continues only while it is taken regularly.
What it is: A disease-modifying anti-rheumatic drug (DMARD) that dampens an overactive immune system to limit or prevent tissue damage and disability, rather than relieving symptoms immediately. It is a long-term treatment — benefits may take 6–12 weeks. Keep taking it even if it doesn't seem to work at first, and even when your symptoms improve. It is initiated by a specialist for SLE (lupus), rheumatoid arthritis, polymyositis/dermatomyositis, and other autoimmune and inflammatory diseases, and is also used to allow steroid dose reduction. Use with caution (reduced doses) in severe liver or kidney problems, or bone marrow problems. A TPMT enzyme blood test is done before prescribing: low TPMT means a higher side-effect risk, and very low TPMT may mean it is not suitable.
How it's taken: Tablets once or twice daily with or after food. The dose is based on body weight: start at about 50 mg/day, which may increase to 100–200 mg.
Side effects: Nausea, vomiting, diarrhoea, appetite loss (take with food or at night), hair loss, and skin rashes. Infection risk is increased, and it can affect blood counts and the liver — regular blood tests are required before and during treatment; you must not take azathioprine unless you're having regular blood checks. Report promptly: sore throat, fever, infection signs, unexplained bruising or bleeding, and jaundice. Chickenpox and shingles can be severe and may need antivirals and pausing treatment. There is possibly a slightly increased risk of certain cancers, some skin-related — use sunscreen.
Interactions: Allopurinol (the gout drug) interacts, so your doctor may change the dose or treatment; warfarin can also interact. Discuss all new medicines with your doctor.
Pregnancy: Current guidelines say it can be taken during pregnancy at doses of 2 mg/kg body weight or less; it is important to maintain the mother's health and avoid flares. It may pass into breast milk; current guidelines state that continuing while breastfeeding is safe — discuss with the rheumatology team.
Why the checks: The monitoring is the safety system: blood counts and liver tests are checked regularly because azathioprine can affect both without symptoms, and catching a change early keeps a small dose adjustment from becoming a bigger problem. The enzyme (TPMT) question matters because people who break the drug down slowly need lower doses from day one.
Used for Lupus (SLE) · Rheumatoid arthritis · Polymyositis · Dermatomyositis
Common worries
Why the frequent blood tests at the start?
Azathioprine can lower blood counts and affect the liver, usually silently and usually in the first weeks. Early, frequent tests catch any change while a dose adjustment is all that is needed.
I’ve read about a gene test — do I need it?
Some people lack an enzyme (TPMT) that breaks azathioprine down, so standard doses build up too high. Testing for it — or starting low with close monitoring — is how that risk is managed.
Will it make me lose my hair or feel sick?
Nausea in the first days is the most common complaint and often settles; taking doses with food helps. Significant hair loss is uncommon at rheumatology doses. Report persistent sickness so we can adjust.
Ready to be seen? New patients are seen within 2–4 weeks.