Exemestane (Aromasin ®)
Exemestane is a hormonal therapy drug used to treat breast cancer in women, who have been through their menopause.
It’s best to read this information with our general information about breast cancer or secondary breast cancer in women. We also have information about breast cancer in men, which explains the hormonal therapies used in men.
Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs. Hormonal therapies interfere with 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.
After the menopause, oestrogen is no longer made in the ovaries. Instead, it’s made in the fatty tissues of the body. This happens when an enzyme called aromatase changes other hormones into oestrogen. Exemestane is a drug called an aromatose inhibitor. It blocks this process and reduces the amount of oestrogen in the body.
When exemestane is given
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Exemestane is used to reduce the risk of early breast cancer coming back. You will usually take it after having two or three years of another hormonal drug called tamoxifen.
Exemestane is also used after other hormonal therapies to control breast cancer that has spread to other parts of the body (secondary breast cancer).
Your doctor or nurse will explain how long you should take exemestane for.
Taking your exemestane tablets
You take exemestane as a tablet once a day. You take it at the same time each day, morning or evening.
There are some important things to remember when taking your tablets:
Don’t take a double dose if you forget to take your tablet.
Keep tablets in the original package, and at room temperature away from heat and direct sunlight.
Keep them safe and out of the reach of children.
Get a new prescription before you run out of tablets, and make sure you have plenty for holidays.
Return any remaining tablets to the pharmacist if your treatment is stopped.
Avoid eating grapefruit and drinking grapefruit juice.
Possible side effects of exemestane
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We explain the most common side effects of exemestane here. But we don’t include all the rare ones that are unlikely to affect you. You may get some of the side effects we mention, but you are very unlikely to get all of them. If you are having other drugs as well, you may have some side effects that we don’t list here.
Always tell your doctor or nurse about the side effects you have. They can prescribe drugs to help control them and give you advice about managing them. Don’t stop taking exemestane without talking to your doctor first.
Hot flushes and sweats
These are common and are often mild, but this can vary. Hot flushes and sweats may improve after the first few months. Cutting down on nicotine, alcohol and hot drinks containing caffeine, such as tea and coffee, can help. Dress in layers, so you can remove clothes as needed. Natural fabrics, such as cotton, may feel more comfortable.
If hot flushes are troublesome, tell your doctor. Low doses of certain antidepressant drugs can help to reduce them.
Joint and muscle pain
You may have pain and stiffness in your joints, and sometimes in your muscles, while taking exemestane. Let your doctor and nurse know if this happens. They can prescribe painkillers and give you advice. Being physically active and maintaining a healthy weight can help reduce joint pain and help to keep them flexible. Let your doctor know if it doesn’t get better.
Feeling sick/ indigestion or tummy pain.
Any sickness is usually mild, but let your doctor or nurse know if this happens. Try taking your exemestane tablets with food or at night. Exemestane may also cause indigestion or tummy pain. Let them know if you have any of these symptoms. They can prescribe drugs to help.
Tiredness and lack of energy
You may feel tired, sleepy or feel like you have no energy when you start taking exemestane. Try to pace yourself until this improves. It’s important to get the right balance of having enough rest and being physically active. Going for regular short walks will help you to feel less tired. If you feel sleepy, don’t drive or use machinery.
If you have headaches, let your doctor or nurse know. They can usually be controlled with non-prescription painkillers.
Diarrhoea or constipation
Any diarrhoea is usually mild. If it doesn’t get better, your doctor can prescribe drugs to control it. Make sure you drink at least two litres (three and a half pints) of fluid every day if you have diarrhoea.
Exemestane can also cause constipation. Drinking at least two litres of fluids (three and a half pints) every day will help. Try to eat more foods that contain fibre (such as fruit, vegetables and wholemeal bread) and take some regular gentle exercise.
Difficulty sleeping and mood changes
If you have trouble getting to sleep, try having a warm bath or a hot milky drink before bed. Relaxation techniques, tapes or CDs can also help. Less commonly, women may feel low in mood while taking exemestane. Talk to your nurse or doctor if this happens. They can suggest ways to help with this.
You may get a mild skin rash. Tell your doctor or nurse if this happens. It’s very important to contact your doctor straight away if you get a severe skin rash.
Some women notice that their hair becomes thinner while taking exemestane. This is usually mild. Your hair will get thicker after treatment finishes.
Exemestane may cause dizziness. Let your doctor or nurse know if this is a problem.
Less common side effects of exemestane
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Taking exemestane for a few years increases your risk of bone thinning, which is called osteoporosis. This can increase your risk of a broken bone (fracture). You will usually have bone density scans to check the bone health before and during treatment.. If you are at risk of osteoporosis, your doctor may prescribe drugs called bisphosphonates to protect your bones. They will also usually advise you to take calcium and vitamin D supplements. Regular walking, eating a healthy diet, not smoking and sticking to sensible drinking guidelines will also help.
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’s more common in women taking exemestane. Tell your doctor if you have these symptoms.
Side effects can usually be controlled or improved. Always let your doctor or nurse know about any side effects you have so they can help you feel better.
Exemestane may cause changes in the way your liver works. You are very unlikely to notice any problems. Your doctor will take regular blood samples to check your liver is working properly
Other information about exemestane
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If you have ongoing problems
Most of the time side effects can be controlled or managed. But for a few women, they can be more troublesome. If this happens, make sure you talk to your cancer doctor or nurse. They can usually suggest ways to improve your side effects. If things don’t improve, go back to your doctor or nurse. They may suggest you try something else.
It’s really important not to stop taking exemestane without telling your doctor, as this may affect the success of your treatment. If side effects are very troublesome and can’t be managed, your cancer doctor may suggest you take a different type of hormonal therapy.
Build up of fluid
You may get swollen hands or feet, and sometimes pain, because of fluid build up. If you notice this or any other swelling, let your doctor know.
Exemestane can interact with other drugs. This includes medicines you can buy in a shop or chemist. Tell your doctor about any medicines you are taking, including ones you can buy for yourself, complementary therapies and herbal drugs.
Medical or dental treatment
If you need to go into hospital for any reason other than cancer, always tell the doctors and nurses that you are taking exemestane. Explain you are taking hormonal therapy and that no one should stop or restart without checking with your cancer doctor first. Tell them the name of your cancer doctor so they can ask for advice.
Always tell your dentist you are taking exemestane.
The information in this section has been produced in accordance with the following sources and guidelines:
electronic Medicines Compendium (eMC). www.medicines.org.uk (accessed May 2014).
Sweetman, et al. Martindale: The Complete Drug Reference. 37th edition. 2011. Pharmaceutical Press.
If you’d like further information on the sources we use, please feel free to contact us.
Thank you to Bruce Burnett, Consultant Pharmacist, who reviewed this information.
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