Mercaptopurine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- darkening of the skin
- hair loss
Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:
- pale skin
- shortness of breath
- sore throat, fever, chills, or other signs of infection
- swelling in the legs, ankles, or feet
- unusual bruising or bleeding
- yellowing of the skin or eyes
- loss of appetite
- swelling of the stomach area
- pain in the upper right part of the stomach
Taking mercaptopurine may increase the risk that you will develop a new cancer. Some people who took mercaptopurine to treat Crohn's disease or ulcerative colitis developed hepatosplenic T cell lymphoma (HSTCL), a very serious form of cancer that often causes death within a short time. Tell your doctor if you experience any of the following symptoms: stomach pain; fever; unexplained weight loss; night sweats or easy bruising or bleeding. Talk to your doctor about the risks of taking this medication.
Mercaptopurine may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.