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Mercaptopurine (Mercaptopurine) - Side Effects and Adverse Reactions



The principal and potentially serious toxic effects of mercaptopurine are bone marrow toxicity and hepatotoxicity (see WARNINGS and PRECAUTIONS).


The most frequent adverse reaction to mercaptopurine is myelosuppression. The induction of complete remission of acute lymphatic leukemia frequently is associated with marrow hypoplasia. Patients without TPMT enzyme activity (homozygous-deficient) are particularly susceptible to hematologic toxicity, and some patients with low or intermediate TPMT enzyme activity are more susceptible to hematologic toxicity than patients with normal TPMT activity (see WARNINGS, Bone Marrow Toxicity), although the latter can also experience severe toxicity. Maintenance of remission generally involves multiple-drug regimens whose component agents cause myelosuppression. Anemia, leukopenia, and thrombocytopenia are frequently observed. Dosages and also schedules are adjusted to prevent life-threatening cytopenias.


Hyperuricemia and/or hyperuricosuria may occur in patients receiving mercaptopurine as a consequence of rapid cell lysis accompanying the antineoplastic effect. Renal adverse effects can be minimized by increased hydration, urine alkalinization, and the prophylactic administration of a xanthine oxidase inhibitor such as allopurinol. The dosage of mercaptopurine should be reduced to one third to one quarter of the usual dose if allopurinol is given concurrently.


Intestinal ulceration has been reported. Nausea, vomiting, and anorexia are uncommon during initial administration, but may increase with continued administration. Mild diarrhea and sprue-like symptoms have been noted occasionally, but it is difficult at present to attribute these to the medication. Oral lesions are rarely seen, and when they occur they resemble thrush rather than antifolic ulcerations.


The administration of mercaptopurine has been associated with skin rashes and hyperpigmentation. Alopecia has been reported.

Drug fever has been very rarely reported with mercaptopurine. Before attributing fever to mercaptopurine, every attempt should be made to exclude more common causes of pyrexia, such as sepsis, in patients with acute leukemia.

Oligospermia has been reported.


Below is a sample of reports where side effects / adverse reactions may be related to Mercaptopurine. The information is not vetted and should not be considered as verified clinical evidence.

Possible Mercaptopurine side effects / adverse reactions in 24 year old female

Reported by a health professional (non-physician/pharmacist) from Netherlands on 2011-10-03

Patient: 24 year old female

Reactions: Epstein-Barr Virus Infection, Lymphoma

Suspect drug(s):

Possible Mercaptopurine side effects / adverse reactions in 32 year old male

Reported by a health professional (non-physician/pharmacist) from United States on 2011-10-04

Patient: 32 year old male

Reactions: Joint Swelling, Colitis Ulcerative, Acne, Erythema Nodosum, Rash Maculo-Papular

Suspect drug(s):
    Indication: Product Used FOR Unknown Indication
    Start date: 2011-06-01

    Indication: Colitis Ulcerative
    Start date: 2011-05-01
    End date: 2011-01-01

Other drugs received by patient: Apriso; Prednisone

Possible Mercaptopurine side effects / adverse reactions in 49 year old male

Reported by a health professional (non-physician/pharmacist) from United States on 2011-10-05

Patient: 49 year old male

Reactions: Pityriasis Rosea, Meningoradiculitis, Herpes Zoster

Adverse event resulted in: hospitalization

Suspect drug(s):

See index of all Mercaptopurine side effect reports >>

Drug label data at the top of this Page last updated: 2012-05-01

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