Patient Medicine Information
Why do I need this medicine?
Mercaptopurine is used on its own or together with other medicines to treat cancer of the white blood cells (leukaemia).

This medicine may be used to treat other conditions as decided by your doctor.
How do I take this medicine?
Take Mercaptopurine exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.

This medicine is available as a tablet or as an oral suspension.

If you have been given a tablet, take it on an empty stomach, at least 1 hour before or 2 hours after a meal. Swallow it whole with a glass of water.

If you are taking an oral suspension, shake the bottle well before you take it to ensure that the liquid is evenly mixed. Use the oral dosing syringe provided to measure out your prescribed dose. Syringe can be reused. Wash well and dry the syringe after using.

Try to take it at the same time each day.

Mercaptopurine must be taken regularly for it to be effective. Continue taking this medicine even when you feel better. Do not stop taking it unless instructed by the doctor.
What should I do if I have forgotten to take this medicine?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.

DO NOT double a dose under any circumstances.

If you often forget to take your medicine, let your doctor and pharmacist know.
When should I not use this medicine?
Alert your doctor if your disease is resistant to prior therapy with Mercaptopurine.

Do not take this medicine if you are pregnant or planning to have a baby soon. If you become pregnant while being treated with Mercaptopurine, alert your doctor immediately. This medicine may cause harm to your unborn child. You must use proven birth control methods while taking this medicine.

Do not breastfeed while you are being treated with this medicine.
What should I take note of while taking this medicine?
Inform your doctor if you have the following conditions:
  • liver disease
  • kidney disease
Individuals who are poor metabolisers of TPMT or have NUDT15 gene mutation may experience enhanced side effects of this medicine (e.g. myelosuppression, a bone marrow disorder leading to decreased blood cells production). Your doctor may perform genetic testing before giving you this medicine to know if it is suitable for you. If you know you have this gene type, inform your doctor. Monitor for any signs of infection, unexpected bruising or bleeding and let your doctor know immediately.

Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly. Routine blood tests, gene type test, liver and kidney function test may be needed while you are being treated with this medicine. Your doctor will advise you about how often you need to have these tests.
What side effects could I experience?
Mercaptopurine may cause any of the following side effects: nausea, vomiting, diarrhoea, loss of appetite and rash.

Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
  • signs of infection (fever, sore throat or mouth ulcers)
  • unusual bleeding or bruising
  • yellowing of the skin or eyes
  • stomach pain that radiates to your back and feels worse after eating (sign of inflammation of the pancreas)
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Can I take this with other medicines?
Inform your doctor and pharmacist if you are taking any of these medicines:
  • medicines for viral infections e.g. ribavirin
  • medicines for gout e.g. allopurinol
  • medicines for cancer e.g. methotrexate
  • blood-thinning medicines e.g. warfarin
  • antibiotics e.g. sulfamethoxazole, trimethoprim

This list does not include all medicines that may interact with Mercaptopurine.

Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
What special dietary instructions should I follow?
Avoid alcohol.
How should I store this medicine?
Store in a cool, dry place away from the reach of children.

Medicines must not be used past the expiry date.

As Mercaptopurine is a cancer medicine, always return any unused or expired tablets or oral suspension to the clinic, hospital or pharmacy for disposal. Do not throw it away in the household waste.
This information is independently developed by MIMS based on mercaptopurine-oral and is provided for your reference only. It is not a replacement for and should only be used in conjunction with full consultation with a licensed healthcare professional, the information provided by your pharmacist and/or the manufacturer of the medication. It may not contain all the available information you require and cannot substitute professional medical care, nor does it take into account all individual circumstances. Although great effort has been made to ensure content accuracy, we shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2022 MIMS. All rights reserved. Powered by
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