Generic name: mercaptopurine [ mer-KAP-toe-PURE-een ]
Brand names: Purixan, Purinethol
Dosage forms: oral suspension (100 mg/5 mL), oral tablet (50 mg)
Drug class: Antimetabolites

Medically reviewed by Drugs.com on Mar 15, 2024. Written by Cerner Multum.

What is mercaptopurine?

Mercaptopurine is used to treat acute lymphoblastic or lymphocytic leukemia. Mercaptopurine is sometimes given with other cancer medications.

Mercaptopurine may also be used for purposes not listed in this medication guide.

Mercaptopurine side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Mercaptopurine may cause serious side effects. Call your doctor at once if you have:

• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath;

• liver problems--loss of appetite, nausea, vomiting, diarrhea, upper stomach pain, swelling in your midsection, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

• symptoms of lymphoma--fever, night sweats, tiredness, stomach bloating, feeling full, weight loss.

Common side effects of mercaptopurine may include:

• low blood cell counts;

• bruising or bleeding;

• nausea, vomiting, loss of appetite;

• diarrhea;

• rash, changes in skin color;

• hair loss; or

• general ill feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Warnings

You should not use mercaptopurine if you have ever used mercaptopurine or thioguanine and they were not effective in treating your condition.

Some people using mercaptopurine have developed a rare fast-growing type of lymphoma (cancer). This condition affects the liver, spleen, and bone marrow, and it can be fatal.

Call your doctor at once if you have symptoms of lymphoma, such as: fever, night sweats, tiredness, stomach bloating, feeling full, easy bruising or bleeding, or weight loss.

Before taking this medicine

You should not use this medicine if you are allergic to mercaptopurine or thioguanine, or if you have ever used mercaptopurine or thioguanine and they were not effective in treating your condition.

Mercaptopurine may cause a rare type of lymphoma (cancer) of the liver, spleen, and bone marrow that can be fatal. Talk with your doctor about your own risk.

Using mercaptopurine may also increase your risk of developing other types of cancer. Ask your doctor about your specific risk.

Tell your doctor if you have ever had:

• liver disease;

• kidney disease;

• an inherited condition in which your body cannot produce enough of the enzyme thiopurine methyltransferase (TPMT);

• any type of viral, bacterial, or fungal infection; or

• ulcerative colitis (treated with mesalamine, sulfasalazine, or similar medicines).

Mercaptopurine may harm an unborn baby, especially when used during the first trimester. Use effective birth control to prevent pregnancy, and tell your doctor if you become pregnant.

You should not breastfeed while taking mercaptopurine.

How should I take mercaptopurine?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Use care when handling mercaptopurine tablets or oral suspension. mercaptopurine may be dangerous if it gets in your eyes or on your skin. If this occurs, wash your skin with soap and water or rinse your eyes with water. Seek medical attention if you have redness, itching, or swelling even after rinsing off the medicine. Ask your doctor or pharmacist how to dispose of unused medicine no longer needed.

Mercaptopurine can increase your risk of bleeding, infection, or liver problems. You will need frequent medical tests. Your next dose may be delayed based on the results.

Mercaptopurine can affect your kidneys. Drink plenty of liquids to keep your kidneys working properly.

You may be given other medication to help prevent serious side effects on your kidneys. Keep using this medicine for as long as your doctor has prescribed.

Store mercaptopurine at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Early symptoms of an overdose may include loss of appetite, nausea, vomiting, or diarrhea. Later symptoms may include fever or flu-like symptoms.

What should I avoid while taking mercaptopurine?

Do not receive a "live" vaccine while using mercaptopurine. The vaccine may not work as well and may not fully protect you from disease. Live vaccines include measles, mumps, rubella (MMR), polio, rotavirus, typhoid, yellow fever, varicella (chickenpox), zoster (shingles), and nasal flu (influenza) vaccine.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.

What other drugs will affect mercaptopurine?

Mercaptopurine can harm your liver, especially if you also use certain medicines for infections, tuberculosis, depression, birth control, hormone replacement, high cholesterol, heart problems, high blood pressure, seizures, pain, or arthritis (including Tylenol, Advil, Motrin, or Aleve).

Tell your doctor about all your other medicines, especially:

• allopurinol;

• olsalazine, mesalazine, sulfasalazine or similar medicines;

• sulfamethoxazole and trimethoprim; or

• warfarin (Coumadin, Jantoven).

This list is not complete. Other drugs may affect mercaptopurine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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

Medical Disclaimer

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