mercaptopurine at a glance
Medicine class
Cytotoxic antimetabolite and purine analogue
Licensed role
Specialist treatment of acute lymphoblastic and acute promyelocytic leukaemia
Blood tests
Regular blood-count and liver-function monitoring is essential
Food and dairy
Take consistently with or without food, and keep tablets separate from milk and dairy products
What is mercaptopurine used for?
The selected tablet is licensed for acute leukaemia under specialist supervision. Some inflammatory-disease uses are established but are not covered by this product's licence.
Licensed: acute lymphoblastic leukaemia in adults, adolescents and children.
Licensed: acute promyelocytic leukaemia.
Non-licensed specialist use: inflammatory bowel disease, including Crohn's disease and ulcerative colitis.
Non-licensed specialist use: autoimmune hepatitis in selected patients.
How does mercaptopurine work?
Mercaptopurine is converted inside cells into active thioguanine nucleotides. These disrupt purine production and nucleic acids, restricting the growth and survival of rapidly dividing cells. This can produce anticancer effects and suppress immune-driven inflammation.
mercaptopurine preparations and strengths
Tablet
Route: Oral
Strengths: 50 mg
How to take mercaptopurine
Follow the specialist team's instructions and check the dispensing label. Swallow tablets with water and take them consistently in relation to food. The selected product information advises evening administration and separation from milk or dairy products. Handle this cytotoxic treatment as little as possible, wash hands before and afterwards, and do not crush tablets unless specifically instructed by a specialist or pharmacist.
Keep the method of taking it—with or without food—consistent.
Keep tablets separate from milk and other dairy products as directed in the product information.
Carers should use disposable gloves when handling tablets and avoid contact with skin or mucous membranes.
Return unwanted tablets to a pharmacy or treatment centre rather than placing them in household waste.
mercaptopurine side effects
Common or expected effects
- Reduced production of white blood cells and platelets, usually detected through blood tests
- Anaemia
- Loss of appetite
- Nausea or vomiting
- Abnormal liver function, hepatotoxicity or impaired bile flow
- Pancreatitis when used for inflammatory bowel disease
Get urgent medical advice
- Fever, sore throat or other infection symptoms, which can indicate dangerously low white-cell levels
- Unexplained bruising or bleeding, which can indicate low platelets
- Yellow skin or eyes, dark urine or marked itching, which may indicate liver injury or cholestasis
- Severe upper abdominal pain, especially with vomiting, which may indicate pancreatitis
- New rash, drug fever, joint pain or facial swelling, which may indicate hypersensitivity
- Breathing difficulty or rapidly developing facial swelling, requiring emergency help
mercaptopurine in pregnancy
Mercaptopurine should be used in pregnancy only after specialist assessment of maternal benefit and fetal risk. Current pregnancy information does not show good evidence that mercaptopurine itself harms the baby, but treatment and the underlying illness require specialist review. Thiopurines have also been linked to intrahepatic cholestasis of pregnancy, so new itching or jaundice needs prompt assessment. Do not stop prescribed treatment abruptly after discovering a pregnancy; contact the specialist team.
mercaptopurine while breastfeeding
The selected tablet product information advises against breastfeeding during treatment. Some specialist services note that milk exposure appears very low in non-cancer settings and may reach a different conclusion after individual assessment. Discuss feeding decisions with the specialist and breastfeeding team.
mercaptopurine interactions
Mercaptopurine has clinically important interactions. A specialist or pharmacist should check prescribed, over-the-counter and herbal products before they are started or stopped.
Allopurinol, oxipurinol or thiopurinol
These inhibit mercaptopurine breakdown and can greatly increase toxicity, requiring specialist-led treatment adjustment and monitoring.
Febuxostat and other xanthine oxidase inhibitors
These may increase mercaptopurine exposure; concomitant use is generally not recommended without specialist management.
Yellow fever vaccine
Concomitant use is contraindicated because an immunocompromised person may develop severe or fatal vaccine-associated disease.
Common questions about mercaptopurine
Answers are fully visible for fast scanning and source review.
What is mercaptopurine used for?
The selected tablet is licensed for acute lymphoblastic and acute promyelocytic leukaemia. Specialists also use it without a licence for conditions such as inflammatory bowel disease and autoimmune hepatitis.
Can mercaptopurine be taken with food?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.