Mercaptopurine is an antimetabolite. It interferes with the making of DNA, which stops fast-growing cells such as leukaemia cells from multiplying, and calms the immune system.

What Mercaptopurine Is Used For

Acute lymphoblastic leukaemia (maintenance treatment)
Some other leukaemias, under specialist care
Crohn's disease and ulcerative colitis

Common Side Effects

Low blood counts
Nausea and loss of appetite
Mouth ulcers
Liver changes
Higher risk of infection

Precautions

Mercaptopurine needs regular blood tests. Report fever, sore throat, bruising or yellowing skin straight away. Tell your doctor if you take allopurinol or febuxostat, as they greatly increase its effect. Avoid live vaccines and pregnancy during treatment.

This page is general information only. It is not a substitute for advice from your doctor or pharmacist, and it does not include dosage. Always follow the directions given to you and read the leaflet inside the pack.