Temozolomide is a chemotherapy drug usually given to treat a type of brain tumour known as a glioma. This information should ideally be read with our general information about chemotherapy and your type of cancer.
What temozolomide looks like
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Temozolomide is available as 5mg, 20mg, 100mg, 140mg, 180mg and 250mg capsules.
The capsules should be swallowed whole with plenty of water. They should not be opened or chewed. You should take the capsules at the same time every day on an empty stomach, either an hour before or an hour after food. It's important to make sure you take the capsules exactly as you have been directed by your doctor.
Chemotherapy is usually given as a course of several sessions (cycles) of treatment over a few months. The length of your treatment and the number of cycles you have will depend on the type of brain tumour you're being treated for. Your nurse or doctor will discuss your treatment plan with you.
Before you begin your treatment your doctor will arrange for you to have blood tests. You'll usually be given anti-sickness drugs before and/or during your treatment.
Each person’s reaction to chemotherapy is different. Some people have very few side effects while others may experience more. The side effects described below won't affect everyone who has temozolomide and may be different if you're having more than one type of chemotherapy drug.
We have outlined the most common side effects but haven't included those that are rare and unlikely to affect you. If you notice any effects that aren't listed below, discuss them with your doctor, chemotherapy nurse or pharmacist.
Risk of infection
Temozolomide can reduce the number of white blood cells, which help fight infection. White blood cells are produced by the bone marrow. If the number of your white blood cells is low you'll be more prone to infections. A low white blood cell count is called neutropenia.
Neutropenia effect can begin seven days after treatment, and your resistance to infection usually reaches its lowest point 10-14 days after chemotherapy. The number of your white blood cells will then increase steadily and usually return to normal levels within 21-28 days.
Contact your doctor or the hospital straight away if:
your temperature goes above 38°C (100.4°F)
you suddenly feel unwell, even with a normal temperature.
You'll have a blood test before having more chemotherapy to check the number of white blood cells in your blood. Occasionally, it may be necessary to delay your treatment if the number of your blood cells (blood count) is still low.
Temozolomide is sometimes given at the same time as a six-week course of radiotherapy. Your blood cell count will be monitored throughout the course of treatment to make sure the number of white blood cells doesn't get too low.
Bruising and bleeding
Temozolomide can reduce the production of platelets, which help the blood to clot. Tell your doctor if you have any unexplained bruising or bleeding, such as nosebleeds, bleeding gums, blood spots or rashes on the skin. You may need to have a platelet transfusion if your platelet count is low.
Temozolomide can reduce the number of red blood cells, which carry oxygen around the body. A low red blood cell count is called anaemia. This may make you feel tired and breathless. Tell your doctor or nurse if you have these symptoms. You may need to have a blood transfusion if the number of red blood cells becomes too low.
Feeling sick (nausea) and being sick (vomiting)
This may begin soon after the treatment is given and can last for a few days. Your doctor can prescribe very effective anti-sickness (anti-emetic) drugs to prevent or greatly reduce nausea and vomiting. If the sickness isn't controlled, or if it continues, tell your doctor; they can prescribe other anti-sickness drugs that may be more effective.
Some anti-sickness drugs can cause constipation. Let your doctor or nurse know if this is a problem.
Temozolomide can cause diarrhoea. This can usually be easily controlled with medicine, but tell your doctor if it's severe or continues. It's important to drink plenty of fluids if you have diarrhoea.
You may get constipated. This can usually be helped by drinking plenty of fluids, eating more fibre and doing some gentle exercise. You may need to take medicine (laxatives) to help. Your doctor can prescribe these or you can buy them at a pharmacy.
Loss of appetite
Some people lose their appetite while they’re having chemotherapy. This can be mild and may only last a few days. If it doesn’t improve you can ask to see a dietitian or specialist nurse at your hospital. They can give you advice on improving your appetite and keeping to a healthy weight.
You may notice that food tastes different. Normal taste usually comes back after treatment finishes. A dietitian or specialist nurse at your hospital can give you advice about ways of coping with this side effect.
Some people find that temozolomide causes headaches. Let your doctor or nurse know if you develop headaches as they can give you painkillers to relieve this.
Feeling tired is a common side effect of chemotherapy, especially towards the end of treatment and for some weeks after it’s over. It’s important to try to pace yourself and get as much rest as you need. Try to balance this with some gentle exercise, such as short walks, which will help. If tiredness is making you feel sleepy, don’t operate or drive machinery.
Raised blood sugar
Temozolomide may cause a temporary increase in the level of sugar in your blood. Some signs of a raised blood sugar level are feeling thirsty, needing to pass urine more often and feeling hungry. If you get any of these let your doctor or nurse know.
If you're diabetic you may need to check your blood sugars more regularly and you may have to adjust your insulin or oral therapy, but you should let your doctor or nurse know first.
Less common side effects
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A skin rash can sometimes occur while you're having treatment with temozolomide. It’s important to let your doctor know if this happens. Your doctor can prescribe medicine to help with this.
This is rare, but your hair may thin, or occasionally fall out completely. If this happens, it usually begins 3-4 weeks after starting treatment, although it may occur earlier. You may also have thinning and loss of eyelashes, eyebrows and hair in other areas of the body. This is temporary and your hair will start to grow back once the treatment has finished. Your hair may grow back straighter, curlier, finer or a slightly different colour than it was before treatment. Your nurse can give you advice about coping with hair loss.
If you're having temozolomide with a course of radiotherapy, the radiotherapy will cause hair loss within the treatment area. Any hair loss due to the radiotherapy may be permanent.
Rarely, temozolomide can cause you to feel breathless for a short while. Contact your doctor if this happens.
Fever and chills
These may occur from the time your treatment is given, but they don’t usually last long. Your doctor may prescribe medicines to reduce these effects.
It’s important to let your doctor know straight away if you feel unwell or have any severe side effects, even if they’re not mentioned above.
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Risk of developing a blood clot
Cancer can increase the risk of developing a blood clot (thrombosis), and chemotherapy may increase this risk further. A blood clot may cause symptoms such as pain, redness and swelling in a leg, or breathlessness and chest pain. Blood clots can be very serious, so it’s important to tell your doctor straight away if you notice any of these symptoms. Most clots can be treated with drugs that thin the blood. The doctor or nurse can give you more information.
Some medicines, including those you can buy in a shop or chemist, can be harmful to take when you're having chemotherapy. Tell your doctor about any medicines you're taking, including over-the-counter drugs, complementary therapies and herbal drugs.
Temozolomide may cause drowsiness. If you feel drowsy, it’s important not to drive or operate machinery.
Your ability to become pregnant or father a child may be affected by having this treatment. It's important to discuss fertility with your doctor before starting treatment.
It's not advisable to become pregnant or father a child while taking temozolomide as it may harm the developing baby. It's important to use effective contraception while taking this drug and for at least a few months afterwards. You can discuss this with your doctor.
It’s not known whether chemotherapy drugs can be present in semen or vaginal fluids. To protect your partner, it’s safest to either avoid sex or use a barrier form of contraception for about 48 hours after chemotherapy.
There's a potential risk that chemotherapy drugs may be present in breast milk. Women are advised not to breastfeed during chemotherapy and for a few months afterwards.
If you’re admitted to hospital for a reason not related to the cancer, it’s important to tell the doctors and nurses looking after you that you're having chemotherapy treatment. You should tell them the name of your cancer specialist so that they can ask for advice.
It’s a good idea to know who you should contact if you have any problems or troublesome side effects when you’re at home. Your chemotherapy nurse or doctor will give you details of who to contact for advice. This should include ‘out-of hours’ contact details if you need to call someone at evenings, overnight or at the weekend.
Things to remember about temozolomide capsules
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It's important to take your capsules at the right times as directed by your doctor.
Always tell any doctors treating you for non-cancerous conditions that you’re taking a course of chemotherapy capsules that shouldn’t be stopped or restarted without the advice of your cancer specialist.
Keep the capsules in their original packaging, and store them at room temperature away from heat and direct sunlight.
Keep the capsules in a safe place and out of the reach of children.
If your doctor decides to stop treatment, return any remaining capsules to the pharmacist. Don't flush them down the toilet or throw them away.
If you're sick just after taking the tablets, let your doctor know. You may need to take another dose. Don't take another tablet without telling your doctor first.
If you do forget to take a capsule don't take a double dose. Tell your doctor and keep to a regular dose schedule.
This section is based on our temozolomide fact sheet, which has been compiled using information from a number of reliable sources, including:
Sweetman, et al. Martindale: The Complete Drug Reference. 37th edition. 2011. Pharmaceutical Press.
British National Formulary. 62nd edition. 2011. British Medical Association and Royal Pharmaceutical Society of Great Britain.
electronic Medicines Compendium (eMC). www.medicines.org.uk (accessed October 2011).
Perry MC. The Chemotherapy Source Book. 4th edition. 2007. Lippincott Williams and Wilkins.