Purinethol, illustration of tablet form (not a photo of the actual pack)

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Purinethol

Mercaptopurine

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$35.00

50mg · 25 tablets

BrandBranded medicine· By GSK

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About Purinethol

Overview

Purinethol contains mercaptopurine, a medicine used in chemotherapy. It treats acute lymphoblastic leukemia (ALL) in adults and children as part of maintenance treatment combined with other chemotherapy medicines. Inside cells, mercaptopurine is converted into substances that interfere with DNA and RNA and the production of their building blocks, stopping cells from multiplying and causing cell death.

What it treats

Acute lymphoblastic leukemia (ALL) in adults and children, as part of maintenance treatment with combination chemotherapy.

Safety information

Side effects

The most common side effect is reduced blood cell production by the bone marrow, affecting more than 20% of patients. This can cause low red blood cell counts (anemia), low white blood cell counts and low platelet counts. Other side effects reported in 5% to 20% of patients include loss of appetite, nausea, vomiting, diarrhea, feeling generally unwell and rash. Serious side effects that warrant contacting a doctor include severe reductions in blood cell counts, liver damage, suppression of the immune system, treatment-related cancers and macrophage activation syndrome. Aggressive and fatal cases of a cancer called hepatosplenic T-cell lymphoma have occurred. Macrophage activation syndrome requires prompt treatment and stopping mercaptopurine under medical supervision. Regular blood counts and liver blood tests are needed to monitor for harmful effects. Vaccines may be less effective during treatment, and live virus vaccines carry a risk of infection. Mercaptopurine can harm an unborn baby; patients who could conceive should use effective contraception.

Interactions

Tell your doctor if you take allopurinol or warfarin. Allopurinol requires your prescriber to adjust your mercaptopurine treatment. Mercaptopurine may reduce warfarin’s blood-thinning effect.

Using Purinethol

Dosing

Dosing is set by your prescriber. Each health care professional may prescribe medication differently according to a patient's medical history and condition, so follow the directions on your prescription label and speak to your doctor or pharmacist before changing anything.

Storage

Store below 25°C in a dry place, in the original pack, away from direct light and moisture. Do not keep it in a bathroom. Keep all medicines out of the sight and reach of children.

Clinical information on this page is summarised from the US FDA label MERCAPTOPURINE TABLET [GOLDEN STATE MEDICAL SUPPLY, INC.] (DailyMed, retrieved 19 September 2026).

Patient information and references

Official and supporting information to read alongside advice from your prescriber or pharmacist.

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