Azathioprine
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Taken as tablets, usually once a day or split, often with food. A blood test for an enzyme called TPMT is usually done before you start, because some people clear it slowly and need a lower dose.
- Immunosuppression (lupus, vasculitis, steroid-sparing): Usually built up to a dose based on your weight.
Tests while you take it
You will have frequent blood tests at first (weekly for a while), then less often, to check your blood counts and liver. Report signs of infection, unusual bruising, or yellowing of the skin.
What to know
How it is used in lupus
Azathioprine is used to help control lupus and keep it settled. It is often the preferred choice when someone wants to get pregnant, because it can usually be continued safely under specialist care.
Common side effects
The more common effects are stomach upset and lowered blood counts, with a higher chance of infections. Less often it can raise the liver blood tests. Regular blood tests catch these early.
Tests and monitoring
Before starting, your team checks a gene test (called TPMT, and NUDT15 if available) that shows how your body handles the medicine. You then have blood counts and liver tests every 2 weeks for the first 8 weeks, then every 2 months. The gout medicine allopurinol raises azathioprine levels, so tell your team if you take it.
Important cautions
Azathioprine can usually be continued during pregnancy when it is needed, under your specialist's guidance, which is why it is often chosen for people planning a family. Your reviewed pregnancy guidance is on the separate pregnancy page.
What to watch for
- Signs of infection with a fever while on treatment. Contact your team.
- Unusual bruising or bleeding, or feeling very tired or breathless.
- Yellowing of the skin or eyes, or persistent nausea or tummy pain.