Megestrol acetate (Megace ®)
Megestrol acetate is a hormonal therapy drug most commonly used to treat breast cancer that has spread. It is also sometimes used to treat womb or prostate cancer.
Megestrol can also be used to improve symptoms such as hot flushes or loss of appetite. It’s best to read this information with our general information about your type of cancer.
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 cancers rely on hormones to grow. Megestrol is a drug that is similar to the female sex hormone progesterone. It may work by interfering with the hormone balance in the body, which may stop the cancer growing. It may also act directly on cancer cells so that they can’t grow.
Your doctor will discuss the length of treatment that they feel is appropriate for your situation. Treatment may continue for as long as it is effective in controlling your cancer.
Taking your megestrol tablets
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Megestrol is a tablet. You usually take it once a day at the same time each day. Sometimes it is prescribed to be taken in divided doses. Always take your tablets exactly as your nurse or pharmacist explained. This is important to make sure they work as well as possible for you. Here are some important things to remember when taking your tablets:
Take your tablet with a glass of water, with or after food.
If you forget to take your tablet, take one as soon as you remember. If it’s nearly time for your next one, don’t take a double dose.
Keep tablets in their original package at room temperature and away from heat and direct sunlight.
Keep your tablets in a safe place that is out of reach of children.
Get a new prescription before you run out of tablets and make sure you have enough for holidays.
Return any remaining tablets to the pharmacist if your treatment is stopped.
Possible side effects of megestrol
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We explain the most common side effects of megestrol 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 cancer doctor or nurse about the side effects you have. They can prescribe drugs to help control some side effects and they can give you advice about managing them.
If you notice any effects that are not listed here, discuss them with your doctor or nurse.
The most common side effect is feeling hungrier than usual, which may cause you to gain weight. This effect on your appetite will go away when you stop taking the drug. If you’re worried about gaining weight, talk to your doctor or nurse.
Sometimes megestrol is used to help improve appetite in people who have lost interest in food and are losing weight.
Swollen hands, feet and ankles
Your hands, feet and ankles may swell because of fluid building up in them. This is not harmful, but can be uncomfortable. Tell your doctor or nurse if you notice any swelling. The swelling will get better after your treatment ends.
You may feel tired and lack energy while taking megestrol. Pace yourself if you feel tired. Try to balance rest periods with some physical activity.
Feeling sick and indigestion
Some people feel sick, especially during the first few weeks of taking megestrol. Tell your doctor if you are affected. They can prescribe treatment to help.
Megestrol may cause changes to your mood. You may feel anxious or restless. You may also have mood swings or problems sleeping. Tell your doctor or nurse if you have any of these side effects. They can make changes to your treatment if the side effects become a problem.
Some people experience skin rashes. Tell your doctor if this occurs.
Vaginal bleeding in women
Occasionally, women may have light vaginal bleeding (spotting). Let your doctor know if this happens. When you stop taking the drug you may have some bleeding from the vagina, similar to a period.
Less common side effects of megestrol
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High levels of calcium in your blood
Occasionally, women who have breast cancer that has spread to the bones can develop high levels of calcium in their blood. This can happen within the first two weeks of taking megestrol. Your doctor will do regular blood tests to check your calcium levels. If you have symptoms such as feeling tired, feeling thirsty and passing a lot of urine, finding it difficult to think clearly, loss of appetite, pain, constipation, or feeling sick contact your doctor or nurse for advice.
If you have diabetes, your blood sugar levels may be higher than usual while taking megestrol. Your doctor will talk to you about how to manage this. You may need to change your insulin or tablet dose.
Risk of blood clots
This treatment can increase the risk of getting a blood clot. If you have had a blood clot in the past, you should discuss this with your doctor before taking megestrol. Tell your doctor immediately if you have possible symptoms of a blood clot such as chest pain or if you have redness, pain, warmth, swelling or tenderness in an arm or leg.
Other information about megestrol
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It's important to use an effective form of contraception during treatment. Even though women may find that their periods stop while taking megestrol, it is not a contraceptive. Megestrol should not be taken during pregnancy, as it may harm the developing baby.
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 are having hormonal treatment. You should tell them the name of your cancer specialist so that they can ask for advice.
Megestrol 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, vitamins and herbal drugs.
The information in this section has been produced in accordance with the following sources and guideline:
If you’d like further information on the sources we use, please feel free to contact us.
With thanks to: Marilyna Chong, Pharmacist, Cancer services; and the people affected by cancer who reviewed this edition.
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