Tioguanine (Lanvis, thioguanine, 6-TG, 6-tioguanine)

Tioguanine used to be called thioguanine. It is a chemotherapy drug used for acute myeloid leukaemia or acute lymphoblastic leukaemia. It 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 DNA so that they can grow and multiply.

Tioguanine comes as 40mg yellow tablets. Take them on an empty stomach with plenty of water (for example, at least 1 hour before or 2 hours after meals). It is very important that you take tablets according to the instructions your doctor or pharmacist gave you. For example, whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream. You should take the right dose, not more or less. And never stop taking a cancer drug without talking to your specialist first.

You usually have chemotherapy as a course of several cycles of treatment. The treatment plan for tioguanine depends on which type of cancer you have. You can find detailed information about how doctors plan chemotherapy in the chemotherapy section.

Tioguanine side effects are listed below. You can use the underlined links to find out more about each side effect or go to the cancer drug side effects section.

More than 10 in every 100 people have one or more of the side effects listed below.

Temporary drop in the number of blood cells made by the bone marrow, causing

• Increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, sore throat, pain passing urine or feel cold and shivery
• Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
• Bruising more easily due to a drop in platelets – you may have nosebleeds, bleeding gums after brushing your teeth, or lots of tiny red spots or bruises on your arms or legs (known as petechia)

Some of these side effects can be life threatening, particularly infections. You should contact your doctor if you have any of these effects. Your doctor will check your blood counts regularly to see how well your bone marrow is working.

Other common side effects include

• Fatigue (tiredness) during and after treatment – most people find their energy levels are back to normal from 6 months to a year after their treatment ends
• Tioguanine may harm a developing baby so it is not advisable to become pregnant or father a child if you are having this drug – talk about contraception to your doctor or nurse before having the treatment if there is any chance that you or your partner could become pregnant

Between 1 and 10 in every 100 people have one or more of these.

• Diarrhoea is usually well controlled with medicine from your doctor or nurse – drink plenty of fluids if you get diarrhoea
• Loss of appetite
• Feeling or being sick is most likely to start within 24 hours but is usually easily controlled with anti sickness injections and tablets – tell your doctor or nurse if you still have sickness as there will be other medicines you can try
• High uric acid levels in your blood (tumour lysis syndrome) – you will have regular blood tests to check your uric acid levels and may have a tablet called allopurinol to take – drinking plenty of fluids will help to flush out the excess uric acid

Fewer than 1 in 100 people have these.

• A sore mouth or mouth ulcers
• Unsteadiness when walking
• Liver problems that will go back to normal when you stop treatment – this is not likely to harm you but your doctor will take regular blood tests to check your liver
• A skin rash
• Women may stop having periods (amenorrhoea) but this may only be temporary
• Loss of fertility – you may not be able to get pregnant or father a child after treatment so it is important to talk to your doctor before starting treatment if having a baby is important to you

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment, or more side effects may develop as the course goes on. This depends on

• How many times you've had the drug before
• Your general health
• The amount of the drug you have (the dose)
• Other drugs you are having

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. Your chemotherapy nurse, clinic or ward nurse will give you a contact number. You can ring if you have any questions or problems. They can give you advice or reassure you. If in doubt, call them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and other over the counter remedies – some drugs can react together.

You should not have immunisations with live vaccines while you are having this treatment or for at least 6 months afterwards. In the UK, live vaccines include rubella, mumps, measles (usually given together as MMR), BCG and yellow fever. You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with oral vaccines, but not many people in the UK have oral vaccines now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.