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Side Effects


The following serious adverse reactions are described elsewhere in the prescribing information:

Clinical Studies Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Based on multicenter cooperative group ALL trials, the most common adverse reaction occurring in > 20% of patients is myelosuppression including anemia, neutropenia, lymphopenia and thrombocytopenia. Adverse reactions occurring 5 to 20 % include anorexia, nausea, vomiting, diarrhea, malaise, and rash. Rare adverse reactions occuring < 5 % include urticaria, hyperuricemia, oral lesions, elevated transaminases, hyperbilirubinemia, hyperpigmentation, pancreatitis. Oral lesions resemble thrush rather than antifolic ulcerations. Delayed or late toxicities include hepatic fibrosis, hyperbilirubinemia, alopecia, pulmonary fibrosis, oligospermia and secondary malignancies [see WARNINGS AND PRECAUTIONS].

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

Read the Purixan (mercaptopurine oral suspension) Side Effects Center for a complete guide to possible side effects


Certain drugs have been shown to interact with PURIXAN through pharmacokinetic and pharmacodynamic mechanisms. Interactions known to decrease the clearance of PURIXAN include inhibition of first-pass oxidative metabolism by xanthine oxidase and inhibition of thiopurine methyltransferase (TPMT). Consult the labeling of all concurrently used drugs to obtain further information about drug interactions with PURIXAN.


Avoid concomitant use of PURIXAN and allopurinol. Concomitant use of allopurinol with PURIXAN inhibits the first-pass oxidative metabolism of mercaptopurine by xanthine oxidase, leading to mercaptopurine toxicity (bone marrow suppression, nausea, vomiting) [see WARNINGS AND PRECAUTIONS].


Concurrent use of PURIXAN and warfarin may result in decreased anticoagulant effectiveness. Monitor prothrombin time or international normalized ratio (INR) in patients receiving oral anticoagulant therapy with warfarin. Adjustments of the warfarin dose may be necessary in order to maintain the desired level of anticoagulation.


Bone marrow suppression may be increased when PURIXAN is combined with other drugs whose primary or secondary toxicity is myelosuppression. Enhanced marrow suppression has been noted in some patients also receiving trimethoprim-sulfamethoxazole. Monitor CBC and adjust the dose of PURIXAN for severe neutropenia and thrombocytopenia [see WARNINGS AND PRECAUTIONS].

Aminosalicylate Derivatives

Concurrent use of PURIXAN and aminosalicylate derivatives (e.g., olsalazine, mesalamine, or sulfasalazine) may inhibit the TPMT enzyme, resulting in an increased risk of bone marrow suppression. Should aminosalicylate derivatives and PURIXAN be coadministered, use the lowest possible doses of each drug and closely monitor the patient for bone marrow suppression [see WARNINGS AND PRECAUTIONS].

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 4/12/2016

Side Effects

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