Mercaptopurine is also called Xaluprine. It is a chemotherapy drug used to treat some types of
You might also have as part of a clinical trial.
Find out more about your cancer type
How does mercaptopurine work?
Mercaptopurine is one of a group of chemotherapy drugs known as anti metabolites. These drugs stop cells making and repairing DNA. Cancer cells need to make and repair
How do you have mercaptopurine?
Mercaptopurine comes as pale yellow tablets and as a pink to brown liquid (oral suspension). The liquid medicine is called Xaluprine.
Taking mercaptopurine tablets
You swallow the tablets whole with lots of water. You can take them with food, or on an empty stomach. You should continue taking the tablets the way you started that is either with food or on an empty stomach.
You should take the tablets at the same time in the evening.
You should take the right dose, not more or less.
Talk to your specialist or advice line before you stop taking a cancer drug.
Taking mercaptopurine liquid
Your nurse or pharmacist will show you how to measure the dose of liquid mercaptopurine using a syringe. You wear disposable gloves while doing this so that the drug doesn't come into contact with your skin.
You take mercaptopurine in the evening, with food or on an empty stomach. But whichever you choose, you should do the same thing each day. You should drink some water after taking the liquid.
You should not take the tablets or liquid at the same time as milk or dairy products. You can take them:
- 1 hour before milk or dairy products
- 2 hours after milk or dairy products
If you take too much mercaptopurine
If you accidentally take more mercaptopurine than you should you might feel sick, be sick or have diarrhoea.
Tell your doctor or go to a hospital straight away. Take the medicine pack with you.
If you forget to take mercaptopurine
Don't take a double dose to make up for the dose that you forgot. Tell your doctor or nurse.
How often do you have mercaptopurine?
You usually have mercaptopurine as a course of several
Your doctor, nurse or pharmacist will tell you how often you should take mercaptopurine for.
You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.
How often and how severe the side effects are can vary from person to person. They also depend on what other treatments you're having.
When to contact your team
Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:
- you have severe side effects
- your side effects aren’t getting any better
- your side effects are getting worse
Early treatment can help manage side effects better.
We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.
Common side effects
These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:
Increased risk of getting an infection
Increased risk of getting an infection is due to a drop in white blood cells. Symptoms include a change in temperature, aching muscles, headaches, feeling cold and shivery and generally unwell. You might have other symptoms depending on where the infection is.
Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection.
Bruising, bleeding gums or nosebleeds
This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae).
Occasional side effects
These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:
- feeling or being sick
- breathlessness and looking pale (due to low red blood cell counts) and tiredness
- sore mouth
- changes to how your liver works. It can also cause the death of liver cells.
- blocked bile ducts
Rare side effects
This side effects happens in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:
- loss of appetite
- skin rash
- inflammation of the pancreas, symptoms include severe tummy pain, feeling or being sick, a high temperature or you may have loose poo
- aching muscles
- high temperature
- risk of developing another cancer
- allergic reaction
Other side effects
There isn't enough information to work out how often this side effect happens.
Mercaptopurine can make your skin sensitive to sunlight or UV light.
Don’t use sunbeds or sit in the sun. Cover up or use a sunscreen if you go out in the sun. Remember to put sun cream on your head or wear a hat if you have lost any hair there.
Find out more about sun safety
Coping with side effects
We have more information about side effects and tips on how to cope with them.
What else do I need to know?
Other medicines, foods and drink
Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.
Lactose and mercaptopurine
This drug contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.
Pregnancy and contraception
This drug may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment with this drug and for at least 3 months afterwards.
Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner falls pregnant while having treatment.
It is not known whether this treatment affects fertility in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.
Don’t breastfeed during this treatment because the drug may come through into your breast milk.
Treatment for other conditions
Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment. For example, if you need treatment for anything else, including teeth problems.
Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having. Ask your doctor or pharmacist how long you should avoid live vaccinations.
In the UK, live vaccines include rubella, mumps, measles, BCG, yellow fever and one of the shingles vaccines called Zostavax.
You can have:
- other vaccines, but they might not give you as much protection as usual
- the flu vaccine (as an injection)
- the coronavirus (COVID-19) vaccine - talk to your doctor or pharmacist about the best time to have it in relation to your cancer treatment
Members of your household who are aged 5 years or over are also able to have the COVID-19 vaccine. This is to help lower your risk of getting COVID-19 while having cancer treatment and until your
Contact with others who have had immunisations - You can be in contact with other people who have had live vaccines as injections. Avoid close contact with people who have recently had live vaccines taken by mouth (oral vaccines) such as the oral typhoid vaccine. Sometimes people who have had the live shingles vaccine can get a shingles type rash. If this happens they should keep the area covered.
If your immune system is severely weakened, you should avoid contact with children who have had the flu vaccine as a nasal spray as this is a live vaccine. This is for 2 weeks following their vaccination.
Babies have the live rotavirus vaccine. The virus is in the baby’s poo for about 2 weeks and could make you ill if your immunity is low. Get someone else to change their nappies during this time if you can. If this isn't possible, wash your hands well after changing their nappy.
More information about this treatment
For further information about this treatment go to the electronic Medicines Compendium (eMC) website.
You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.