Drugs A - Z

Mercaptopurine Oral tablet

It interferes with the growth of cancer cells and can reduce immune system activity

Generic Name: mercaptopurine

Brand Names: Purinethol

There is an FDA Alert for this drug. Click here to view it.

Special Alerts:

[Posted 04/14/2011] ISSUE: FDA continues to receive reports of a rare cancer of white blood cells (known as Hepatosplenic T-Cell Lymphoma or HSTCL, primarily in adolescents and young adults being treated for Crohn’s disease and ulcerative colitis with medicines known as tumor necrosis factors (TNF) blockers, as well as with azathioprine, and/or mercaptopurine. TNF blockers include infliximab (Remicade), etancercept (Enbrel), adalimumab (Humira), certolizumab pegol (Cimzia) and golimumab (Simponi).

BACKGROUND: HSTCL is an aggressive (fast-growing) cancer and is usually fatal. The majority of cases reported were in patients being treated for Crohn’s disease or ulcerative colitis, but also included a patient being treated for psoriasis and two patients being treated for rheumatoid arthritis. FDA is now updating the number of reported cases of HSTCL.

Although most reported cases of HSTCL occurred in patients treated with a combination of medicines known to suppress the immune system, including the TNF blockers, azathioprine, and/or mercaptopurine, there have been cases reported in patients receiving azathioprine or mercaptopurine alone.

  • Educate patients and caregivers about the signs and symptoms of malignancies such as HSTCL so that they are aware of and can seek evaluation and treatment of any signs or symptoms. These may include splenomegaly, hepatomegaly, abdominal pain, persistent fever, night sweats, and weight loss.
  • Monitor for the emergence of malignancies when a patient has been treated with TNF blockers, azathioprine, and/or mercaptopurine.
  • Know that people with rheumatoid arthritis, Crohn's disease, ankylosing spondylitis, psoriatic arthritis and plaque psoriasis may be more likely to develop lymphoma than the general U.S. population. Therefore, it may be difficult to measure the added risk of TNF blockers, azathioprine, and/or meracaptopurine.

Read the Drug Safety Communications for other specific recommendations for Healthcare Professionals and Patients and the Data Summary for additional information. For more information visit the FDA website at: [Web] and [Web].

What is this medicine?

MERCAPTOPURINE, 6-MP (mer kap toe PYOOR een) is a chemotherapy drug. It interferes with the growth of cancer cells and can reduce immune system activity. It is used to treat certain types of acute leukemia.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
  • infection (especially virus infection such as chickenpox or herpes)
  • kidney disease
  • liver disease
  • low blood counts like low platelets, red blood cells, or white blood cells
  • thiopurine methyltransferase (TPMT) deficiency
  • an unusual or allergic reaction to mercaptopurine, azathioprine, other chemotherapy, other medicines, foods, dyes, or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. Take your medicine at regular intervals. Do not take it more often than directed. Do not stop taking except on your doctor's advice.

Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for selected conditions, precautions do apply.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose and skip your missed dose. Do not take double or extra doses.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
  • azathioprine

This medicine may also interact with the following medications:

  • allopurinol
  • balsalazide
  • medicines to increase blood counts like filgrastim, pegfilgrastim, sargramostim
  • other chemotherapy drugs like doxorubicin
  • mesalazine, 5-ASA
  • olsalazine
  • sulfasalazine
  • vaccines
  • warfarin

What should I watch for while using this medicine?

This drug may make you feel generally unwell. This is not uncommon, as chemotherapy can affect healthy cells as well as cancer cells. Report any side effects. Continue your course of treatment even though you feel ill unless your doctor tells you to stop.

To protect your kidneys, drink water or other fluids as directed while you are taking this medicine.

In some cases, you may be given additional medicines to help with side effects. Follow all directions for their use.

Call your doctor or health care professional for advice if you get a fever, chills or sore throat, or other symptoms of a cold or flu. Do not treat yourself. This drug decreases your body's ability to fight infections. Try to avoid being around people who are sick.

This medicine may increase your risk to bruise or bleed. Call your doctor or health care professional if you notice any unusual bleeding.

Be careful brushing and flossing your teeth or using a toothpick because you may get an infection or bleed more easily. If you have any dental work done, tell your dentist you are receiving this medicine.

Avoid taking products that contain aspirin, acetaminophen, ibuprofen, naproxen, or ketoprofen unless instructed by your doctor. These medicines may hide a fever.

Do not become pregnant while taking this medicine. Women should inform their doctor if they wish to become pregnant or think they might be pregnant. There is a potential for serious side effects to an unborn child. Talk to your health care professional or pharmacist for more information. Do not breast-feed an infant while taking this medicine.

Men should inform their doctors if they wish to father a child. This medicine may lower sperm counts.


Last Updated: August 28, 2009
Licensed from
The Healthline Site, its content, such as text, graphics, images, search results, HealthMaps, Trust Marks, and other material contained on the Healthline Site ("Content"), its services, and any information or material posted on the Healthline Site by third parties are provided for informational purposes only. None of the foregoing is a substitute for professional medical advice, examination, diagnosis, or treatment. Always seek the advice of a physician or other qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the Healthline Site. If you think you may have a medical emergency, call your doctor or 911 immediately. Please read the Terms of Service for more information regarding use of the Healthline Site.
Advertisement
Advertisement