Megestrol acetate (Megace)

Megestrol acetate is a type of hormone treatment. It is also called Megace or megestrol. It is a man made version of the hormone progesterone. Progesterone is one of the female hormones but men also produce a small amount of it. 

Megestrol acetate is a treatment for the following cancers that have come back or spread from where they started.

  • breast cancer
  • womb cancer

It is also a treatment for poor appetite. Your doctor might suggest you take it if you have lost weight because of cancer or its treatment. Doctors might also use it as a treatment for women who have hot flushes due to their cancer or its treatment. 

How does megestrol acetate work?

Megestrol can interfere with the hormone balance in the body so that the body makes smaller amounts of the hormones that some cancers depend on to grow. It may also interact with other hormones or have a direct effect on the cancer to stop it growing.

How often do you take megestrol acetate?

Megestrol acetate are tablets.

You take them for at least 2 months. This is to find out if they are working. You usually take megestrol acetate once a day, at the same time each day. But sometimes the dose is divided up, so that you take the tablets a couple of times a day.

You can take them for many years. 

Taking your tablets

You must take tablets according to the instructions your doctor or pharmacist gives you.

You should take the right dose, not more or less.

Talk to your specialist or advice line before you stop taking a cancer drug.

If you miss a dose and remember within a few hours, you can take it as soon as possible. But if it is almost time for your next dose, miss the forgotten dose and carry on as before. Don't take an extra dose to make up for the one that you missed.

If you accidentally take too many tablets, let your doctor know, or go to your nearest accident and emergency department straight away.


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

What are the side effects of megastrol acetate?

How often and how severe the side effects are can vary from person to person. They also depend on what other treatments you're having. For example, your side effects could be worse if you're also having other drugs or radiotherapy.

When to contact your team

Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 
  • your side effects aren’t getting any better
  • your side effects are getting worse

Early treatment can help manage side effects better. 

Contact your doctor or nurse immediately if you have signs of infection, including a temperature above 37.5C or below 36C.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects, but you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

Increased appetite and weight gain

Feeling hungrier can make it difficult to keep your weight down. Your appetite will go back to normal when you stop the treatment but some people need to diet to lose the extra weight.

Talk to your nurse or your dietitian about how to safely control your weight.

Hot flushes and sweats

We have some tips for coping with hot flushes and the possible treatments for men and women. Talk to your doctor if your hot flushes are hard to cope with. They might be able to prescribe you some medicines.

Shortness of breath

Megestrol acetate can cause you to be short of breath. Tell your doctor or nurse if it happens. 

Rounded face

You may find that your face becomes more rounded. This is sometimes called a moon face.

Raised blood pressure

Tell your doctor or nurse if you have headaches, nosebleeds, blurred or double vision or shortness of breath. Your nurse will check your blood pressure regularly.

Raised blood sugar level

You have regular blood and urine tests to check this. If you have diabetes you may need to check your blood sugar levels more often than usual. 


Constipation is easier to sort out if you treat it early. Drink plenty of fluids and eat as much fresh fruit and vegetables as you can. Try to take gentle exercise, such as walking. Tell your doctor or nurse if you are constipated for more than 3 days. They can prescribe a laxative.

Blood clots

Blood clots can develop in the deep veins of your body, usually the leg. This is called deep vein thrombosis (DVT). A blood clot can be very serious if it travels to your lungs (pulmonary embolism), although this isn’t common.

Symptoms of a blood clot include:

•    pain, redness and swelling around the area where the clot is and may feel warm to touch
•    breathlessness
•    pain in your chest or upper back – dial 999 if you have chest pain
•    coughing up blood

Tell your doctor immediately or go to A&E if you have any symptoms of a blood clot.

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • feeling sick - this is usually mild
  • fluid build up might cause swelling of the fingers and toes and weight gain
  • women might have vaginal bleeding (spotting) that is not part of your period
  • women might stop having periods (amenorrhoea) but this may be temporary
  • headaches - mild painkillers such as paracetamol might help
  • you might feel tired, weak or lacking energy
  • your hair may thin but is not usually noticeable
  • skin rash that may be itchy
  • you might have mood changes if you do talk to your doctor or nurse
  • men might lose the ability to have an erection talk to your doctor they can help
  • you may pass wind (flatulence) more often
  • you might pass urine more often during the day
  • diarrhoea that is usually mild
  • high level of calcium in the blood - you'll have regular blood tests to check this
  • heart changes that might slightly increase your risk of a heart attack - your doctor will check your heart regularly
  • you might get pain in the area of the cancer, when you first start taking megestrol - your doctor or nurse can suggest painkillers to take
  • a small number of people have an allergic reaction
  • carpal tunnel syndrome can cause a weak grip, pain, numbness or tingling in your hand - tell your doctor

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know?

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or father a child while you're having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Lactose intolerance

This drug contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.

More information about this treatment

For further information about this treatment go to the electronic Medicines Compendium (eMC) website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

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