Exemestane is a hormonal therapy drug used to treat breast cancer. It can be given alone or with other types of treatment. It is best to read this information with our general information about hormonal therapies and the type of cancer you have.
Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.
Hormones are chemicals that our bodies make. Hormones act as messengers and help control how cells and organs work. Hormonal therapies are drugs that change the way hormones are made or how they work in the body.
Many breast cancers rely on the hormone oestrogen to grow. This type of breast cancer is called oestrogen receptor-positive (ER positive) breast cancer.
In women who have been through the menopause, oestrogen is no longer made in the ovaries. Instead, it is made in the fatty tissues of the body. This happens when an enzyme (a type of protein) called aromatase changes other hormones into oestrogen.
Exemestane is a type of drug called an aromatase inhibitor. It stops aromatase from working. This reduces the amount of oestrogen in the body.
Exemestane is used to treat breast cancer in women. You may have it after other treatments, to reduce the risk of breast cancer coming back.
Exemestane is often used to treat women who have been through the menopause. But it may also be given to women who have not had their menopause. In this situation, women will usually have exemestane with a drug that stops the ovaries making oestrogen. They may also have it with surgery to remove the ovaries.
Exemestane is also sometimes used to treat breast cancer in men.
Your doctor or nurse will explain why you are having exemestane and how long you will take it for.
We explain the most common side effects of this treatment here. We also include some less common side effects. You may get some of the side effects we mention, but you are unlikely to get all of them.
If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.
Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.
Serious and life-threatening side effects
Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.
Contact the hospital
Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.
Hot flushes and sweats
These are common. During a flush, your neck and face may feel warm and look red. Flushes can last for a few seconds or for up to 10 minutes. You may have sweats then feel cold and clammy. Some people feel anxious or irritable during a hot flush.
There are things you can do to try to reduce flushes:
- Wear clothes made from natural fabrics, such as cotton.
- Dress in layers of clothes that you can remove as needed.
- Use cotton sheets and have layers of bedding.
- Keep the room temperature cool or use a fan.
- Have cold drinks rather than hot ones. Try to avoid drinks with caffeine in them.
You may have fewer hot flushes and sweats as your body adjusts to hormonal treatment. Or your doctor can prescribe drugs to help. Some people continue to have flushes and sweats, but they usually stop a few months after treatment finishes.
Women coping with hot flushes can read more in our information about managing menopausal symptoms.
Muscle or bone pain
You may get pain in your muscles or bones. If this happens, tell your doctor so they can give you painkillers. Let your doctor or nurse know if it does not get better.
Any sickness is usually mild, but let your doctor or nurse know if this happens. Try taking your tablets with food or at night.
Indigestion or tummy pain
This treatment may cause indigestion or tummy pain. Let your doctor know if you have any of these symptoms. They can prescribe drugs to help.
Loss of appetite
If you don’t have an appetite or can’t face big meals, try to eat small, frequent meals or snacks instead of three meals a day.
Feeling tired is a common side effect. It is often worse towards the end of treatment and for some weeks after it has finished. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.
If you have headaches, let your doctor or nurse know. They can usually be controlled with mild painkillers.
Diarrhoea is usually mild. If it doesn’t get better, your doctor can prescribe drugs to control it. Make sure you drink at least 2 litres (3½ pints) of fluid every day if you have diarrhoea.
Mood and behaviour changes
Some people find they have a low mood while taking exemestane. Or you may have problems concentrating, feel anxious or have difficulty sleeping. Talk to your nurse or doctor if you have these changes so they can give you support and advice.
This treatment may affect your skin. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day. The treatment may cause a rash, which may be itchy.
Always tell your doctor or nurse about any skin changes. They can give you advice and may prescribe creams or medicines to help. Any changes to your skin are usually temporary and improve when treatment finishes.
It’s very important to contact your doctor straight away if you get a severe skin rash.
Your hair may become thinner when you are taking this treatment. This is usually mild. Ask your nurse for advice if you are worried about this.
Exemestane may cause dizziness. Let your doctor or nurse know if this is a problem.
Pain, numbness and tingling in hand and fingers
These symptoms may be due to carpal tunnel syndrome, which is caused by pressure on a nerve in the wrist. It is more common in people taking exemestane. Tell your doctor if you have these symptoms.
Swollen hands, feet and ankles
Effects on the liver
Treatment may affect how your liver works. This is usually mild. You will have blood tests to check how well your liver is working.
Rarely, this treatment can cause inflammation of the liver (hepatitis). Tell your doctor straight away if the whites of your eyes or your skin turn yellow or if you become unwell with itching or you have pain on the right side of your tummy.
Bone thinning (osteoporosis)
If you take this treatment for several months or more, you may get bone thinning. This is called osteoporosis. This can increase your risk of a broken bone (fracture). You may have bone density scans to check your bone health before and during treatment.
Doing regular exercise, such as walking, can improve your bone health. Eating a healthy diet can help too. Your doctor may prescribe drugs called bisphosphonates to help protect your bones. They may also advise you to take calcium and vitamin D supplements.
Risk of infection
Exemestane can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection.
If you have an infection, it is important that it is treated as soon as possible. Contact your GP if you think you have possible symptoms of infection. Signs of an infection can include:
- having a temperature over 37.5°C (99.5°F)
- feeling shaky
- a cough
- a sore throat
- needing to pass urine often.
You will have regular blood tests during treatment.
Bruising and bleeding
This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot.
Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:
- bleeding gums
- tiny red or purple spots on the skin that may look like a rash.
Some people may need a drip to give them extra platelets. This is called a platelet transfusion.
Blood clot risk
Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:
- pain, redness or swelling in a leg or arm
- chest pain.
If you have any of these symptoms, contact a doctor straight away.
A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.
Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.
Women are advised not to breastfeed while having this treatment. This is because the drugs could be passed to the baby through breast milk.
Some medicines can affect the hormonal treatment or be harmful when you are having it. This includes medicines you can buy in a shop or chemist. Tell your cancer doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.
Medical and dental treatment
If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.
If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.
Problems with glucose
These tablets contain a type of sugar called glucose. If you have been told by a doctor that you cannot digest some sugars, talk to your doctor before taking this drug.