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Mercaptopurine (Purinethol®, Purixan™)

About This Drug

Mercaptopurine is used to treat cancer. It is given by mouth (orally).

Possible Side Effects

  • Bone marrow suppression. This is a decrease in the number of white blood cells, red blood cells, and platelets. This may raise your risk of infection, make you tired and weak (fatigue), and raise your risk of bleeding.
  • Nausea and vomiting (throwing up)
  • Diarrhea (loose bowel movements)
  • Decreased appetite (decreased hunger)
  • Changes in your kidney function
  • General discomfort, a feeling of being unwell
  • Rash

Note: Not all possible side effects are included above.

Warnings and Precautions

  • Changes in your liver function, which may be life-threatening
  • Severe bone marrow depression, which may be life-threatening
  • Decrease immune function, which increases your risk of infection
  • This drug may raise your risk of getting a second cancer, such as lymphoma, skin cancers, sarcomas and uterine cervical cancer.

Note: Some of the side effects above are very rare. If you have concerns and/or questions, please discuss them with your medical team.

Important Information

  • This medicine is available in tablets and oral suspension. Do not use them interchangeably.

How to Take Your Medication

  • Tablets: Swallow the medicine whole. Do not chew, break or crush it.
  • Oral suspension: Shake bottle vigorously for 30 second prior to using. If using a syringe for dispensing, ensure the syringe is cleaned with soap and water, rinse and dried well in between usage. Once the bottle has been opened, it should be used within 8 weeks.
  • Missed dose: If you vomit or miss a dose, contact your doctor for further instructions. Do not take 2 doses at the same time or extra doses.
  • Handling: Wash your hands after handling your medicine, your caretakers should not handle your medicine with bare hands and should wear latex gloves.
  • This drug may be present in the saliva, tears, sweat, urine, stool, vomit, semen, and vaginal secretions. Talk to your doctor and/or your nurse about the necessary precautions to take during this time.
  • Storage: Store tablets and oral suspension in the original container at room temperature, in a dry place. Keep the lid tightly closed.
  • Disposal of unused medicine: Do not flush any expired and/or unused medicine down the toilet or drain unless you are specifically instructed to do so on the medication label. Some facilities have take-back programs and/or other options. If you do not have a take-back program in your area, then please discuss with your nurse or your doctor how to dispose of unused medicine.

Treating Side Effects

  • Manage tiredness by pacing your activities for the day.
  • Be sure to include periods of rest between energy-draining activities.
  • To decrease the risk of infection, wash your hands regularly.
  • Avoid close contact with people who have a cold, the flu, or other infections.
  • Take your temperature as your doctor or nurse tells you, and whenever you feel like you may have a fever.
  • To help decrease the risk of bleeding, use a soft toothbrush. Check with your nurse before using dental floss.
  • Be very careful when using knives or tools.
  • Use an electric shaver instead of a razor.
  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you throw up or have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack of water in the body from losing too much fluid).
  • To help with nausea and vomiting, eat small, frequent meals instead of three large meals a day. Choose foods and drinks that are at room temperature. Ask your nurse or doctor about other helpful tips and medicine that is available to help stop or lessen these symptoms.
  • If you have diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping.
  • Ask your nurse or doctor about medicine that can lessen or stop your diarrhea.
  • To help with decreased appetite, eat small, frequent meals. Eat foods high in calories and protein, such as meat, poultry, fish, dry beans, tofu, eggs, nuts, milk, yogurt, cheese, ice cream, pudding, and nutritional supplements.
  • Consider using sauces and spices to increase taste. Daily exercise, with your doctor’s approval, may increase your appetite.
  • If you get a rash do not put anything on it unless your doctor or nurse says you may. Keep the area around the rash clean and dry. Ask your doctor for medicine if your rash bothers you.
  • Use sunscreen with SPF 30 or higher when you are outdoors even for a short time. Cover up when you are out in the sun. Wear wide-brimmed hats, long-sleeved shirts, and pants. Keep your neck, chest, and back covered.

Food and Drug Interactions

  • There are no known interactions of mercaptopurine with food.
  • Check with your doctor or pharmacist about all other prescription medicines and over-the-counter medicines and dietary supplements (vitamins, minerals, herbs and others) you are taking before starting this medicine as there are known drug interactions with mercaptopurine. Also, check with your doctor or pharmacist before starting any new prescription or over-the-counter medicines, or dietary supplements to make sure that there are no interactions.

When to Call the Doctor

Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

  • Fever of 100.4° F (38° C) or higher
  • Chills
  • Tiredness that interferes with your daily activities
  • Feeling dizzy or lightheaded
  • Easy bleeding or bruising
  • Sore throat
  • Nausea that stops you from eating or drinking and/or is not relieved by prescribed medicines
  • Throwing up more than 3 times a day
  • Lasting loss of appetite or rapid weight loss of five pounds in a week
  • Diarrhea, 4 times in one day or diarrhea with lack of strength or a feeling of being dizzy
  • Pain in your abdomen that does not go away
  • Decreased urine, or very dark urine
  • New rash and/or itching
  • Rash that is not relieved by prescribed medicines
  • Develop sensitivity to sunlight/light
  • Signs of a local infection such as red, tender, swollen areas of the skin (you may not have pus if your white blood cell count is low)
  • Signs of possible liver problems: dark urine, pale bowel movements, bad stomach pain, feeling very tired and weak, unusual itching, or yellowing of the eyes or skin
  • If you think you may be pregnant

Reproduction Warnings

  • Pregnancy warning: This drug can have harmful effects on the unborn baby. Women of childbearing potential should use effective methods of birth control during your cancer treatment. Let your doctor know right away if you think you may be pregnant.
  • Breastfeeding warning: It is not known if this drug passes into breast milk. For this reason, women should talk to their doctor about the risks and benefits of breastfeeding during treatment with this drug because this drug may enter the breast milk and cause harm to a breastfeeding baby. 
  • Fertility warning: In men and women both, this drug may affect your ability to have children in the future. Talk with your doctor or nurse if you plan to have children. Ask for information on sperm or egg banking.

Revised June 2019

This patient information was developed by Via Oncology, LLC © 2019. This information 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.

CLIENT acknowledges that the Via Pathways and Via Portal are information management tools only, and that Via Oncology, LLC has not represented the Via Pathways or Via Portal as having the ability to diagnose disease, prescribe treatment, or perform any other tasks that constitute the practice of medicine. The clinical information contained in the Via Pathways and Via Portal are intended as a supplement to, and not a substitute for, the knowledge, expertise, skill, and judgment of physicians, pharmacists and other healthcare professionals involved with patient care at CLIENT facilities.