6-Mercaptopurine (Generic Name)

Other Names: Purinethol, mercaptopurine, 6-MP

About This Drug

6-mercaptopurine is used to treat cancer. This drug is given by mouth.

Possible Side Effects (More Common)

  • Mild bone marrow depression. This is a decrease in the number of white blood cells, red blood cells, and platelets. Bone marrow depression usually occurs 11 to 23 days after the drug is given, but may not occur for up to six weeks after the drug is given. Bone marrow depression may increase your risk of infection, fatigue, and bleeding.
  • Soreness of the mouth and throat may occur with high doses of this drug. You may have red areas, white patches, or sores that are painful.
  • Changes in liver enzymes. Liver enzymes will be checked as needed.

Possible Side Effects (Less Common)

  • Skin and tissue irritation. You may have redness, pain, warmth, or swelling at the IV site. This irritation occurs if the drug leaks out of the vein into the surrounding tissue.
  • Diarrhea. This effect is rare, but is severe if it occurs.
  • Headache
  • Red rash around the mouth, upper chest, and back of the hands. The rash may be scaly or raised.
  • Darkening of skin. This effect is rare. This darkening is usually temporary and will fade when treatment is completed.
  • Darkening or partial loss of fingernail and toenail beds
  • Decreased appetite
  • Blood in the urine or stool
  • Crystals in the urine. This may occur with high doses of this drug.
  • Lung tissue changes

Sexual Problems and Reproductive Concerns

  • In men and women both, this drug may temporarily or permanently affect your ability to have children. This cannot be determined before your therapy. In men, this drug may interfere with your ability to make sperm, but it should not change your ability to have sexual relations. In women, menstrual bleeding may become irregular or stop while you are receiving this drug. Do not assume that you cannot become pregnant if you do not have a menstrual period. Women may experience signs of menopause like vaginal dryness or itching.
    • Pregnancy warning: This drug may have harmful effects on the unborn child, so effective methods of birth control should be used during your cancer treatment.
    • Speak with your doctor or nurse if you plan to have children.  Ask for information on sperm or egg banking.
    • Genetic counseling is available to you to discuss the effects of this drug therapy on future pregnancies. In addition, a genetic counselor can review the potential risks of problems in the fetus due to this medication if an exposure during pregnancy has occurred.
    • Breast feeding warning: Women are advised not to breast feed during treatment because this drug could enter the breast milk and seriously harm a breast feeding infant.

Treating Side Effects

  • Mouth care is very important. Your mouth care should consist of gently brushing with a very soft tooth brush and rinsing your mouth with a mixture of 1/2 teaspoon of salt in 8 ounces of water or 1/2 teaspoon of sodium bicarbonate (baking soda) in 8 ounces of water. This should be done at least after every meal and at bedtime.
  • Avoid mouthwash that contains alcohol. Avoid alcohol and smoking because they can irritate your mouth and throat.
  • Ask your doctor or nurse about medication to help prevent or lessen nausea and vomiting.
  • Drink 6-8 cups of fluids every day unless your doctor has told you to restrict your fluid intake due to another medical condition. A cup is 8 ounces of fluid. If you vomit or have diarrhea, you should drink more fluids so that you do not become dehydrated.
  • Do not put anything on your rash unless your doctor or nurse says you may. Keep the area around the rash clean and dry.

Food and Drug Interactions

There are no known interactions of 6-mercaptopurine and any food. This drug is known to interact with allopurinol, olsalazine, azathioprine, febuxostat, and echinacea. If you are on any of these medications or unsure if you are discuss this with your doctor before starting this medication. This drug may interact with other medication. Tell your doctor and pharmacist about all the medication and dietary supplements (vitamins, minerals, herbs and others) that you are currently taking. The safety and effectiveness of dietary supplements and alternative diets are often unknown. Using these might unexpectedly affect your cancer or interfere with your treatment. Until more is known, you should not use dietary supplements or alternative diets without your cancer doctor's advice.

Allergic Reactions

Allergic reactions including anaphylaxis are rare but may occur in some patients. Signs of allergic reactions to this drug may include swelling of the face, feeling like your tongue or  throat are swelling, shortness of breath, rash (dry scaling), itching, fever, chills, dizziness, and/or palpitations (feeling your heart beat rapidly).  Do not take another dose of this drug and seek immediate medical treatment.

When to Call the Doctor

Call your doctor or nurse immediately if you have any of the following symptoms:

  • Temperature of 100.5 F (38 C) or above
  • Chills
  • Difficulty catching your breath
  • Unusual bleeding or bruising
  • Uncontrolled nausea that prevents you from eating or drinking
  • Vomiting more than twice in one day
  • Redness, pain, warmth, or swelling at the IV site
  • Chest pain
  • Blood in the urine
  • Crystals in the urine
  • Coughing
  • Dizziness

Call your doctor or nurse as soon as possible if you have any of the following symptoms:

  • Painful mouth or throat that makes it difficult to eat or drink
  • Diarrhea of five or six stools in one day or diarrhea with weakness or lightheadedness
  • Nausea unrelieved by prescribed medication
  • Headache unrelieved by prescribed medication
  • Yellowing of the skin or eyes
  • Persistent loss of appetite or weight loss of five pounds or more in one week
  • Extreme tiredness that interferes with normal activities
  • Rash that is bothersome

Revised December 2011

©  UPMC | Affiliated with the University of Pittsburgh Schools of the Health Sciences
Supplemental content provided by A.D.A.M. Health Solutions. All rights reserved.

For help in finding a doctor or health service that suits your needs, call the UPMC Referral Service at 412-647-UPMC (8762) or 1-800-533-UPMC (8762). Select option 1.

UPMC is an equal opportunity employer. UPMC policy prohibits discrimination or harassment on the basis of race, color, religion, ancestry, national origin, age, sex, genetics, sexual orientation, marital status, familial status, disability, veteran status, or any other legally protected group status. Further, UPMC will continue to support and promote equal employment opportunity, human dignity, and racial, ethnic, and cultural diversity. This policy applies to admissions, employment, and access to and treatment in UPMC programs and activities. This commitment is made by UPMC in accordance with federal, state, and/or local laws and regulations.

Medical information made available on UPMC.com is not intended to be used as a substitute for professional medical advice, diagnosis, or treatment. You should not rely entirely on this information for your health care needs. Ask your own doctor or health care provider any specific medical questions that you have. Further, UPMC.com is not a tool to be used in the case of an emergency. If an emergency arises, you should seek appropriate emergency medical services.

For UPMC Mercy Patients: As a Catholic hospital, UPMC Mercy abides by the Ethical and Religious Directives for Catholic Health Care Services, as determined by the United States Conference of Catholic Bishops. As such, UPMC Mercy neither endorses nor provides medical practices and/or procedures that contradict the moral teachings of the Roman Catholic Church.

© UPMC
Pittsburgh, PA, USA UPMC.com