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Mercaptopurine Side Effects

Medically reviewed by Drugs.com. Last updated on May 28, 2020.

For the Consumer

Applies to mercaptopurine: oral suspension, oral tablet

Side effects requiring immediate medical attention

Along with its needed effects, mercaptopurine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking mercaptopurine:

More common

  • Black, tarry stools
  • bleeding gums
  • clay colored stools
  • cough or hoarseness
  • dark urine
  • decreased appetite
  • fever or chills
  • headache
  • loss of appetite
  • lower back or side pain
  • nausea, vomiting
  • painful or difficult urination
  • pale skin
  • pinpoint red spots on the skin
  • rash, itchy skin
  • stomach pain or tenderness
  • swelling of the feet or lower legs
  • trouble with breathing upon exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • yellow eyes or skin

Less common

  • Chest pain
  • joint pain
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands

Incidence not known

Side effects not requiring immediate medical attention

Some side effects of mercaptopurine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

  • Darkening of the skin

Incidence not known

  • Hair loss or thinning of the hair
  • low sperm count

For Healthcare Professionals

Applies to mercaptopurine: oral suspension, oral tablet

Hematologic

Very common (10% or more): Bone marrow suppression (e.g., anemia, leukopenia, thrombocytopenia) (more than 20%)[Ref]

Renal

Frequency not reported: Hyperuricemia[Ref]

Gastrointestinal

Common (1% to 10%): Stomatitis, diarrhea, vomiting, nausea

Uncommon (0.1% to 1%): Pancreatitis, oral ulceration

Very rare (less than 0.01%): Intestinal ulceration[Ref]

Hepatic

Common (1% to 10%): Biliary stasis, hepatotoxicity

Uncommon (0.1% to 1%): Hepatic necrosis

Frequency not reported: Hepatotoxicity[Ref]

Dermatologic

Uncommon (0.1% to 1%): Skin rash

Rare (less than 0.1%): Facial edema, alopecia

Frequency not reported: Photosensitivity reaction[Ref]

Genitourinary

Rare (less than 0.1%): Transient oligospermia[Ref]

Other

Frequency not reported: Fetotoxicity[Ref]

Oncologic

Rare (0.01% to 0.1%): Neoplasms including lymphoproliferative disorders, skin cancers (melanomas and non-melanomas), sarcomas (Kaposi's and non-Kaposi's), uterine cervical cancer in situ

Very rare (less than 0.01%): Secondary leukemia, myelodysplasia

Frequency not reported: Hepatosplenic T-cell lymphoma[Ref]

Immunologic

Uncommon (0.1% to 1%): Bacterial and viral infections, infections associated with neutropenia, drug fever

Frequency not reported: Immunosuppression, macrophage activation syndrome[Ref]

Metabolic

Common (1% to 10%): Anorexia

Frequency not reported: Hypoglycemia In patients with inflammatory bowel disease (IBD) (IBD is not an approved indication of this drug)[Ref]

Nervous system

Uncommon (0.1% to 1%): Arthralgia[Ref]

Cardiovascular

Postmarketing reports: Portal hypertension[Ref]

References

1. "Product Information. Mercaptopurine (mercaptopurine)." Mylan Pharmaceuticals Inc, Morgantown, WV.

2. "Product Information. Purixan (mercaptopurine)." AnovoRx Distribution, Memphis, TN.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.