PrescriptionGiant is a FREE prescription savings program that can save you up to 75% on your prescriptions with or without insurance!


Actual product appearance may differ slightly.

Click the CARD below to print or take a screenshot on your mobile phone or tablet. There is no need to download another app!

If you would like to personalize your card enter your full name in the member name field below the card at this link and click the Update button.

Why is this medication prescribed?

Mercaptopurine, also known by its brand name Purinethol, is a medication that is primarily prescribed to treat certain medical conditions, particularly those related to the overproduction of white blood cells or as part of chemotherapy regimens for specific types of cancer. Here are some of the conditions for which Mercaptopurine may be prescribed:

  • Acute Lymphoblastic Leukemia (ALL): Mercaptopurine is commonly used as part of combination chemotherapy regimens to treat ALL, a type of cancer that affects the white blood cells.
  • Crohn’s Disease: Mercaptopurine may be prescribed to manage and control symptoms of Crohn’s disease, an inflammatory bowel disease.
  • Ulcerative Colitis: It can also be used to treat ulcerative colitis, another inflammatory bowel disease.
  • Autoimmune Disorders: In some cases, Mercaptopurine may be prescribed to manage certain autoimmune disorders, such as rheumatoid arthritis or systemic lupus erythematosus (SLE).

How should this medicine be used?

The exact dosage and duration of Mercaptopurine treatment will depend on the specific medical condition being treated and the individual patient’s response to the medication. It’s crucial to follow your healthcare provider’s instructions carefully when using Mercaptopurine. Here are some general guidelines for using Mercaptopurine:

  • Dosage: The dosage of Mercaptopurine will be determined by your healthcare provider based on your weight, medical condition, and other factors. It is typically taken as an oral tablet.
  • Frequency: Mercaptopurine is usually taken once a day, either with or without food. It’s important to take it at the same time each day.
  • Monitoring: Your healthcare provider will closely monitor your response to Mercaptopurine through blood tests to ensure that it is effectively treating your condition and not causing any adverse effects.
  • Duration: The duration of treatment can vary widely depending on the condition being treated. Some patients may need to take Mercaptopurine for an extended period, while others may only use it for a specific course of chemotherapy.
  • Side Effects: Mercaptopurine can have side effects, including nausea, vomiting, diarrhea, bone marrow suppression (which can lower your blood cell counts), and an increased risk of infection. It’s essential to report any unusual or severe side effects to your healthcare provider.
  • Interactions: Mercaptopurine can interact with other medications, so it’s important to inform your healthcare provider about all the drugs and supplements you are taking.
  • Pregnancy and Contraception: Mercaptopurine should not be used during pregnancy, as it can harm the developing fetus. If you are of childbearing age and sexually active, reliable contraception should be used during Mercaptopurine treatment.

It’s crucial to have regular check-ups and follow-up appointments with your healthcare provider while taking Mercaptopurine to monitor your progress and manage any potential side effects or complications. Never change the dosage or stop taking Mercaptopurine without consulting your healthcare provider, as doing so could have serious consequences for your condition.

Other uses for this medicine

Mercaptopurine (Purinethol) may have some other uses or off-label indications, but it’s primarily prescribed for the conditions mentioned earlier, such as acute lymphoblastic leukemia (ALL), Crohn’s disease, ulcerative colitis, and certain autoimmune disorders. Any use of Mercaptopurine beyond these approved indications should be discussed with and monitored by a healthcare professional.

What special precautions should I follow?

Special precautions should be taken when using Mercaptopurine, and it’s essential to discuss these with your healthcare provider. Here are some key precautions to keep in mind:

  • Pregnancy and Breastfeeding: Mercaptopurine can harm a developing fetus, so it should not be used during pregnancy. If you become pregnant while taking Mercaptopurine, inform your healthcare provider immediately. It is also not recommended during breastfeeding, as it can be excreted in breast milk.
  • Contraception: If you are of childbearing age and sexually active, you should use reliable contraception methods while taking Mercaptopurine and for some time after discontinuing the medication. Discuss contraception options with your healthcare provider.
  • Liver Function: Mercaptopurine is metabolized in the liver, so individuals with liver disease or impaired liver function may require dose adjustments or more frequent monitoring.
  • Kidney Function: Kidney function should also be assessed before and during Mercaptopurine treatment. Dose adjustments may be necessary in individuals with impaired kidney function.
  • Bone Marrow Suppression: Mercaptopurine can cause bone marrow suppression, leading to a decrease in blood cell counts. Regular blood tests are crucial to monitor your blood cell levels. Report any signs of infection (fever, sore throat) or unusual bleeding or bruising to your healthcare provider promptly.
  • Infections: Mercaptopurine can increase the risk of infections. Avoid close contact with people who have contagious illnesses, and promptly report any signs of infection to your healthcare provider.
  • Vaccinations: Live vaccines should be avoided while taking Mercaptopurine, as they may cause severe infections. Consult your healthcare provider about appropriate vaccinations and timing.
  • Medication Interactions: Inform your healthcare provider about all the medications, supplements, and herbal products you are taking, as Mercaptopurine can interact with various drugs, potentially affecting its effectiveness or increasing the risk of side effects.
  • Alcohol and Smoking: It’s advisable to avoid alcohol and smoking while on Mercaptopurine, as they can interact negatively with the medication and contribute to liver damage.
  • Regular Monitoring: Regularly scheduled check-ups and blood tests are crucial to monitor your response to Mercaptopurine and detect any potential side effects or complications early.

Always follow your healthcare provider’s instructions and discuss any questions or concerns you have about Mercaptopurine. They will provide guidance tailored to your specific medical condition and needs.

What special dietary instructions should I follow?

Special Dietary Instructions for Mercaptopurine:

  • Mercaptopurine can be taken with or without food. However, some people may experience stomach upset when taking it on an empty stomach. If this occurs, you can take it with a small meal or a snack.
  • It’s generally a good idea to limit alcohol consumption or avoid it altogether while taking Mercaptopurine, as alcohol can interact with the medication and increase the risk of side effects.

What should I do if I forget a dose?

If you forget to take a dose of Mercaptopurine, follow these general guidelines:

  • If it’s within a few hours of the missed dose, take it as soon as you remember.
  • If it’s close to the time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule.
  • Do not take a double dose to make up for the missed one.
  • If you’re unsure about what to do or if you frequently forget doses, contact your healthcare provider or pharmacist for guidance.

What side effects can this medication cause?

Common side effects of mercaptopurine may include:

  • Nausea and vomiting: These are common side effects and can often be managed with anti-nausea medications.
  • Bone marrow suppression: Mercaptopurine can reduce the production of blood cells in the bone marrow, leading to an increased risk of anemia, infection, and bleeding.
  • Liver problems: It may cause liver function abnormalities, which can be monitored through blood tests.
  • Pancreatitis: Inflammation of the pancreas is a rare but serious side effect of mercaptopurine. Symptoms may include severe abdominal pain, nausea, and vomiting.
  • Skin rash: Some individuals may develop skin rashes while taking this medication.
  • Hair loss: Temporary hair loss or thinning may occur.
  • Increased susceptibility to infections: Due to the suppression of the immune system, individuals taking mercaptopurine may be more susceptible to infections.
  • Gastrointestinal symptoms: These can include diarrhea, abdominal pain, and loss of appetite.
  • Increased sensitivity to sunlight: Some people may experience increased sunburn when exposed to sunlight.
  • Changes in blood cell counts: Mercaptopurine can lead to changes in white blood cell, red blood cell, and platelet counts.
  • Allergic reactions: In rare cases, severe allergic reactions may occur, with symptoms such as swelling of the face, lips, tongue, or throat; difficulty breathing; and hives.
  • Elevated uric acid levels: This medication can lead to high levels of uric acid in the blood, which may cause gout or kidney stones in some individuals.

It’s crucial to follow your healthcare provider’s instructions closely when taking mercaptopurine. They will monitor your blood counts and liver function regularly while you are on this medication to detect and manage any potential side effects. If you experience any unusual or severe side effects, contact your healthcare provider immediately. This medication should only be used under the supervision and guidance of a healthcare professional.

What should I know about storage and disposal of this medication?


  • Store Mercaptopurine at room temperature, away from direct sunlight, heat, and moisture.
  • Keep the medication out of reach of children and pets.
  • Store it in its original container with the lid tightly closed to protect it from humidity.
  • Do not use Mercaptopurine if it has passed its expiration date; safely dispose of any expired medication.


Proper disposal of unused or expired medication is essential to prevent accidental ingestion or harm to the environment. Here’s how to dispose of Mercaptopurine safely:

  • Do not flush Mercaptopurine down the toilet or drain, as it may contaminate water sources.
  • Check with your local pharmacy or healthcare facility if they have a medication take-back program where you can return unused medications.
  • If no take-back program is available, mix the unused Mercaptopurine with an unpalatable substance (such as dirt or cat litter) in a sealable plastic bag and discard it in your household trash. This helps prevent accidental ingestion by children or pets.
  • Remove or obscure any personal information on the medication container before disposal.

In case of emergency/overdose

If you suspect an overdose of Mercaptopurine or experience severe adverse reactions, seek immediate medical attention or contact your local poison control center (1-800-222-1222 in the United States). Symptoms of an overdose may include:

  • Severe nausea or vomiting
  • Diarrhea
  • Abdominal pain
  • Easy bruising or bleeding
  • Signs of infection (e.g., fever, chills)
  • Unusual tiredness or weakness

What other information should I know

  • Always take Mercaptopurine exactly as prescribed by your healthcare provider. Do not alter the dosage or stop taking it without their guidance.
  • Inform all healthcare professionals involved in your care that you are taking Mercaptopurine, as it may interact with other medications or treatments.
  • Mercaptopurine may impair your ability to drive or operate heavy machinery. Be cautious if you experience dizziness, confusion, or other neurological symptoms while taking the medication.
  • Regular follow-up appointments and blood tests are essential to monitor your response to Mercaptopurine and detect any potential side effects or complications early.
  • Do not share Mercaptopurine with others, even if they have a similar medical condition. The medication is prescribed based on individual medical needs.
  • Keep a list of all medications you are taking and share it with your healthcare provider. This includes prescription drugs, over-the-counter medications, herbal supplements, and vitamins.
  • If you have any questions or concerns about Mercaptopurine, its side effects, or its interactions with other medications, discuss them with your healthcare provider. They can provide you with personalized guidance and information.

Always follow your healthcare provider’s instructions and recommendations when using Mercaptopurine to ensure safe and effective treatment for your specific medical condition.

Copyright © 2023