What is megestrol (Megace®)?

Megestrol (Megace®) is a hormonal therapy drug used to treat breast and womb cancer that has spread to other parts of the body. This is called secondary cancer. It may also be used to treat breast and womb cancer that has come back after treatment (recurrent). 

Megestrol can also be used to improve your appetite

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.

How megestrol works

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 cancers need hormones to grow. Megestrol is similar to the female sex hormone progesterone. It works by changing the hormone balance in the body, which may stop the cancer growing. It can also act directly on cancer cells so that they cannot grow.

Taking megestrol tablets

Megestrol comes as tablets you can take at home. Your nurse or doctor will talk to you about your treatment plan.

Always take the tablets exactly as explained. This is important to make sure they work as well as possible for you. Make sure you:

  • swallow them whole with a glass of water
  • take them at the same time every day. 

If you forget to take the tablets, just take your next dose at the usual time. Do not take a double dose unless your doctor tells you to.

Other things to remember about your tablets:

  • Keep them in their original package and at room temperature, away from heat and direct sunlight.
  • Keep them safe and out of sight and reach of children. 
  • If you are sick just after taking the tablets, contact your healthcare team. Do not take another dose. 
  • Get a new prescription before you run out of tablets, and make sure you have plenty for holidays.
  • If your treatment is stopped, return any unused tablets to the pharmacist.

Take all your tablets exactly as they have been explained to you. Do not stop taking any of your tablets unless your doctor tells you to.

About side effects

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.

You will see a doctor, nurse or pharmacist regularly while you are having this treatment. Always tell them about any side effects you have. They can give you drugs to help control most side effects. They can also offer advice to help you cope.

Most side effects can be managed. But sometimes side effects are harder to control. It is important not to stop taking hormonal therapy without telling your doctor. If side effects cannot be managed, your doctor may suggest you take a different type of hormonal therapy.

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.

More information

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.

Common side effects

Increased appetite and weight gain

This treatment can make you feel more hungry than usual. This can cause you to gain weight. This effect on your appetite will go away when you stop taking the drug. If you are worried about gaining weight, talk to your doctor or nurse.

Because of this side effect, this treatment is sometimes used to treat people who have lost interest in food and are losing weight.

Constipation

This treatment can cause constipation. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Hot flushes and sweats

Hot flushes are a common side effect of this treatment. During a flush, your neck and face may feel warm and look red. Flushes may last from a few seconds up to 10 minutes. You may have sweats and 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.
  • Wear layers of clothes that you can remove if you feel hot.
  • Use cotton bed sheets and have layers of bedding that you can remove if you feel hot.
  • Keep room temperatures 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. Flushes and sweats usually stop a few months after treatment finishes, but some people continue to have them.

We have more information about coping with hot flushes. Women can read more about coping with hot flushes in our information about managing menopausal symptoms.

High blood pressure

You will have regular blood pressure checks when taking megestrol. Tell your doctor or nurse if you have ever had any problems with your blood pressure. You should also tell them if you have any headaches.

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
  • breathlessness
  • 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.

Raised blood sugar levels

This treatment can raise your blood sugar levels. If you have a raised blood sugar level, you may:

  • feel thirsty
  • need to pass urine (pee) more often
  • feel tired.

Tell your doctor or nurse if you have these symptoms.

If you have diabetes, your blood sugar levels may be higher than usual. Your doctor will talk to you about how to manage this. You may need to change your insulin or tablet dose.

Rounded face

Your face may become rounded while taking megestrol. This is sometimes called a “moon face”.

Less common side effects

Tiredness

Feeling tired is a common side effect. 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.

Feeling sick

Some people feel sick, especially during the first few weeks of taking this treatment. Tell your doctor if you feel sick. They can prescribe anti-sickness drugs to help.

Mood changes

You may have some mood changes during this treatment. You may feel low or depressed. Let your doctor or nurse know if you notice any changes.

Memory or concentration

You may notice changes in your memory. You may also find it harder to concentrate. To help you remember things, try using:

  • a notebook
  • notes on your phone
  • a calendar.

Skin changes

This treatment may affect your skin. It may cause a rash, which might be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day.

Always tell your doctor or nurse about any changes to your skin. They can give you advice and may prescribe creams or medicines to help. Skin changes usually improve when treatment finishes.

Hair thinning

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.

Change in periods

Your periods will usually stop while you are having this treatment. Sometimes, women may have light vaginal bleeding (spotting). Let your doctor know if this happens. When you stop taking megestrol you may have some bleeding from the vagina, similar to a period.

Sexual effects

Most men lose their sex drive and have erection problems during hormonal therapy. Things often return to normal after you stop taking the drug. But some men continue to have problems after treatment is over. Your doctor can prescribe treatments to help with erection problems. But these treatments will not increase your sex drive.

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 treatment ends.

Tumour flare

If you have this treatment for cancer that has spread to the bones, you may get pain in the bones when you start taking it. Doctors call this tumour flare. Your doctor can give you treatment to help with this.

Diarrhoea

This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you, or having watery or loose stools. If you have a stoma, it will be more active than usual.

If you have diarrhoea:

  • try to drink at least 2 litres (3½ pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods
  • contact the hospital for advice.

Other information

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

Contraception

Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm the developing baby. It is important to use effective contraception during your treatment.

Breastfeeding

Women are advised not to breastfeed while having this treatment. This is because the drugs could be passed to the baby through breast milk.

Fertility

Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

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.

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