Mercaptopurine (Oral)

Mercaptopurine is a cancer medication that is used alongside other medications to treat acute lymphoblastic leukemia.


Mercaptopurine belongs to the group of medications that are known as antimetabolites. They are used alongside other medications for maintenance treatment of acute lymphatic leukemia.

This drug works by interfering with the growth of cancer cells, which are destroyed eventually. Since this drug can affect your normal body cell growth, other effects may also occur. These could be serious and you should report them to a medical professional.

Before you start treatment with this drug, you and your doctor will discuss the benefits this medication offers alongside the associated risks.

You can only obtain this medication via a doctors prescription. It is available in the dosage forms of tablet and suspension.

Conditions treated

  • Acute promyelocytic leukemia

Type of medication

  • Oral tablet

Side effects

Alongside its intended effects, the consumption of this drug could produce a number of unwanted side effects. Not all of these side effects may be present but if they are, you may be required to seek medical attention.

Consult with your doctor right away if you suffer from any of the following side effects whilst taking this drug:

More common

  • Vomiting or nausea

Less common

  • Joint pain

Incidence not known

  • Lower back or side pain

Some of the side effects that occur with this drug don't typically require medical attention, you find that these side effects begin to diaper as your body starts adjusting the medication. However, you can seek advice from a healthcare professional if you are finding these side effects bothersome for ways to reduce the effects. Seek advice from a doctor if any of the following side effects become bothersome or linger.

Less common

  • Darkening of the skin

Incidence not known

You may suffer from other side effects not listed above. Seek advice from your healthcare team if you notice anything strange.


The final dose of this medication will be different for everyone. It will depend on individual factors including your weight, age, and height. Any other medical conditions you suffer from and any other medication you take to treat these conditions. Your healthcare team will also consider the strength of the medication, your duration of treatment and your reaction to the first dose. Do not change your dose unless it has been discussed with your doctor. To do so could increase your risk of side effects or reduce your treatment. The following doses are only guidelines.

For oral dosage forms (tablets or suspension) for the maintenance treatment of acute lymphatic leukemia:

Adults: The final dose is based on body weight and will be determined by your doctor. However, typically you begin with a dose of 1.5 to 2.5 mg per kg of body weight each day, taken as one single dose. Your doctor adjusts your dose as necessary.

Children: The final dose and use will be determined by a doctor.

Missed Dose

If you miss a dose of Mercaptopurine, you need to take it as soon as you remember, unless it's close to your next dose. In this case, you should skip the dose you have missed and return to your original dosing schedule. Don't take double doses.

Proper use

Mercaptopurine is often given in combination with other medications. If you are given a combination of medications, you should ensure that you take each one at the correct time. Don't mix the medications. You should ask your doctor for help in retaining a schedule and a way to remember the correct time to take your medication.

Shake the bottle for at least thirty seconds to ensure that the oral suspension is mixed well. You should measure the dose with a marked measuring adaptor and an oral syringe. Once you are finished, ensure you rinse the dosing syringe with soapy warm water.

While you are using this drug, your doctor or healthcare team may require that you consume extra fluids so that you can increase the amount of urine you pass. This will help keep your kidneys working well and prevent kidney problems.

If you become sick shortly after taking a dose of this drug, seek advice from your doctor. You will be told whether to take your next dose or wait until your scheduled dose.


Drug interactions can occur with this drug and these interactions could cause unwanted side effects or even reduce the effectiveness of the drug in treatment. To limit these interactions occurring, you should give your healthcare team a complete list of all the current medications you are taking, including all prescription and nonprescription drugs, all vitamin supplements and herbal products. You should also make them aware of any other medical conditions you may suffer from as these too could increase your risk of interactions. Your healthcare team will do their best to avoid interactions, but in some cases they are unavoidable.

The use of this medication alongside any of the following is not typically recommended and your doctor may decide not to treat you with this drug or change the drugs you are taking.

The use of this medication alongside any of the following is not typically recommended, but in some cases may be necessary. If you are given both medications at the same time, your doctor will alter some of the doses you are taking or the frequency in which you use either medication.

  • Doxorubicin

The use of this medication alongside any of the following could increase your risk of side effects. However, in some cases, both drugs may be the best treatment for you. If you are given both medications at the same time, your doctor may change the dose or frequency in which you use either medication.

  • Phenprocoumon

Other interactions

Some medications shouldn't be used at or around the time of consuming food or some certain types of food since it could cause interactions. The use of tobacco and alcohol with certain medications can also increase the risk of interactions to occur. You should discuss with your healthcare team about the use of your medication with alcohol, food, or tobacco.

Other Medical Problems

The presence of other medical conditions could affect the use of this medication. Ensure you let your doctor know about any other medical problems, especially:

  • Leukopenia (low white blood cells)


Before you decide to use this medication, there are a number of things to consider. Discuss the following warnings alongside the advice of your doctor before you decide whether this is the best treatment plan for you.


You should let your healthcare team know if you have ever suffered from an allergic reaction to this medication or any other medications. It's also important to make them aware of any other allergies you suffer from including to animals, dyes, preservatives or foods.

Pediatric population

Appropriate studies have not been conducted on the relationship of age to the effects of this in the pediatric population. Therefore efficacy and safety have not been established.

Geriatric population

Appropriate studies conducted to date have not indicated a geriatric-specific problem that could limit the effectiveness of mercaptopurine in the older population. However, older patients are more likely to have age-related liver or kidney problems, which could require a degree of caution or dose adjustment for those patients receiving mercaptopurine.

Use in pregnancy and breastfeeding

This drug is under FDA pregnancy category D. Studies in pregnant women have indicated a risk to the fetus. You should let your doctor know if you are currently pregnant whilst taking this medication or you intend on becoming pregnant. You may need to avoid taking this drug whilst pregnant.

With regards to breastfeeding, it is unknown whether this drug can pass into breast milk during feeding. You should, therefore, let your doctor know if you are breastfeeding and discuss the potential risk and benefits.

It's extremely important that your doctor monitors your progress at regular appointments to ensure that this medication is working correctly. They may also run blood tests to test for unwanted side effects. Your doctor may also conduct genetic testing to test the levels of thiopurine S-methyltransferase in your body.

The use of this medication whilst pregnant can harm an unborn child. It's best to use effective forms of birth control to prevent yourself from getting pregnant. Let your doctor know right away if you think you are pregnant.

Don't use this medication if you are also taking azathioprine. The use of these medications together could produce some serious side effects. You should also not use this medication if you have been treated with thioguanine (Tabloid®) or mercaptopurine in the past and it was not successful.

This mediation could increase your risk of obtaining certain types of cancer. Some young adults and teenagers with ulcerative colitis or Crohn's disease have developed a rare type of cancer known as hepatosplenic T-cell lymphoma (HSTCL). Speak with your doctor if you have unusual bruising, bleeding, or weakness, swollen lymph nodes in the underarms, neck, or groin, or weight loss that you can't explain.

While you are being treated with this drug and after you have stopped treatment with it, don't receive any immunizations without approval from your doctor first. This drug could reduce your body resistance, leaving you with a higher risk of obtaining the infection the vaccine is meant to prevent. In addition, other people living in your home should not take oral polio vaccine since there is a chance they could pass this onto you. You should try to avoid anyone in general who has taken oral polio vaccine. Make sure you are not close to them and do not remain in a room with them for long periods of time. If you can't take these precautions, you need to consider wearing a protective face mask that covers the mouth and nose.

This drug can temporarily lower the number of white blood cells in your blood, which increases your chance of obtaining an infection. It can also lower the number of platelets, which are required for proper blood clotting. There are certain precautions you can take if this occurs, especially when your blood count is low, to reduce the risk of bleeding or infection:

Avoid people with infections if you can. Seek advice from your healthcare team right away if you think you are obtaining an infection or if you get chills or a fever, hoarseness or a cough, side or lower back pain, or difficult or painful urination.

Seek advice from your doctor right away if you notice any unusual bruising or bleeding, tarry, black, stools, blood in the stools or urine or pinpoint red spots on your skin.

Be careful when using dental floss, a regular toothbrush, or toothpick. Your medical dentist or doctor may suggest other ways to clean your gums and teeth. Seek advice from your doctor before you have any dental work.

Don't touch the inside or your nose or your eyes unless you have just washed your hands and have not touched anything else.

Try not to cut yourself when you are using sharp objects such as a toenail or fingernail cutters or safety razor.

Avoid contact sports or other situations where injury or bruising could occur.

Don't stop taking this medication without checking with your healthcare team first.

Seek medical advice immediately if you have tenderness or pain in the upper stomach, pale stools, loss of appetite, dark urine, unusual weakness or tiredness, nausea or yellow skin or eyes. These could be signs of a serious liver problem.

Let your doctor know you are taking this drug before you have any medical tests as the results could be affected by this drug. The results of tests for the amount of uric acid or sugar in the blood measured by sequential multiple analyzers could be affected by this medication.


Ensure you keep this drug out of the reach of children. Don't keep medications you no longer need or have passed their expiry day. Your local pharmacist can give you advice on the best method of disposal for such medications.

Store this medication in a closed container at room temperature and keep it away from moisture, light, and heat. Do not let this medication freeze. Once you have opened it, use the oral suspension within a six-week period.


When used correctly, this drug is successful in the maintenance treatment of acute lymphocytic leukemia. It is used alongside other medications. Due to a large number of effects possible with this drug, it's important that your healthcare doctor is aware of any medications or other medical conditions you suffer from.

The safety and efficacy of this drug have not been established for use in children. You could not use this medication whilst pregnant as to do so could harm your unborn child. You need to let your doctor know if you have fallen pregnant whilst using this medication and take birth control to prevent any pregnancy occurring. You should also let them know if you are currently breastfeeding.

Only take this medication as has been directed by your doctor and do not share this drug with anyone else. You need to use this medication regularly to obtain the greatest benefit from it. To assist you in remembering, you should take this medication at the same time every day. If you require any further information about the practical uses of this medication or you have more questions, you should contact your local healthcare professional or doctor for more advice.