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Trade/other name(s): Megace, Megace ES

Why would this drug be used?

Megestrol is given to treat several types of cancer, including advanced breast cancer and endometrial cancer. It is also used in higher doses to improve appetite in people with weight loss due to cancer or AIDS.

How does this drug work?

Megestrol is a member of the group of drugs known as hormones or hormone antagonists. It is a manmade form of progestin (a female hormone), and its action in the body is similar to the natural hormone progesterone. It is unclear how it stops cancer cells from growing, but the drug appears to compete for hormone receptor sites on the cell. It seems to change the way estrogen stimulates cancer cells. It is also unclear how the hormone increases appetite. However, the weight that is gained appears to be due to an increase in stored fat, rather than water weight or muscle.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have any medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, congestive heart failure, gout, or infections. These conditions may require that your medicine dose, regimen, or timing be changed.
  • If you have diabetes. Megestrol may increase your blood sugar and change your insulin needs. You and your doctor may need to watch your glucose levels closely while you are getting this drug.
  • If you have had blood clots or stroke. Rarely, megestrol can cause blood clots in the leg or arm, the lungs, or brain (stroke).
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. It is important to check with your doctor about what kinds of birth control can be used with this medicine. (See “Precautions” section.)
  • If you are breast-feeding. The drug may pass into breast milk and harm the baby.
  • If you think you might want to have children in the future. This drug may affect fertility. Talk with your doctor about the possible risk with this drug and the options that may preserve your ability to have children.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

People with HIV who are taking indinavir may need to take higher doses of indinavir while on megestrol.

Check with your doctor, nurse, or pharmacist about whether any other medicines, vitamins, herbs, and supplements, or alcohol can cause problems with this medicine.

Interactions with food

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Megestrol acetate is given as either a pill or as liquid taken by mouth. This drug can be given at different strengths and intervals depending on the type of cancer or condition being treated. When used to treat cancer, a dose is usually taken 4 times a day. When used to help appetite, megestrol acetate is usually taken once a day, in the morning. Take this drug exactly as directed by your doctor. If you do not understand the instructions, ask your doctor or nurse to explain them to you. Store the medicine in a tightly closed container away from heat and moisture and out of the reach of children and pets.


Megestrol can affect your blood glucose (sugar) levels. A few people even develop diabetes while taking this drug. If you notice dry mouth, unexplained thirst, poor appetite, and increased urination, talk to your doctor. If you have diabetes, watch your blood sugar carefully.

Megestrol can cause high calcium levels the first couple of weeks it is taken by women with breast cancer that has spread to bones. This is a rare but serious problem. Call your doctor if you notice symptoms such as feeling tired, trouble thinking clearly, lack of appetite, pain, increased thirst and urination, constipation, or nausea and vomiting.

Very rarely, this drug can cause blood clots. Sometimes they form in the arm or leg to cause a deep vein thrombosis, stroke, or blockage in the lungs. Call your doctor or nurse right away if you develop pain in your lower leg (calf), redness or swelling of your arm or leg, shortness of breath, chest pain, coughing up blood, sudden severe headache, numbness, or trouble speaking or moving.

With prolonged use (months to years), some people's adrenal glands stop working well. This can cause dizziness, weakness, nausea, vomiting, poor appetite, weight loss, and low blood pressure, which can be very dangerous. This effect may persist after the megestrol is stopped. Call your doctor right away if you notice these symptoms.

In case of infection or injury, be sure to tell any doctors treating you how long you have taken this drug. You may need extra steroid (cortisone-type) hormones during the time your body is stressed, because the adrenals may not make enough.

During treatment or just after megestrol is stopped, women may notice vaginal bleeding between menstrual periods. Let your doctor know if this bleeding continues.

Some women stop menstruating altogether after taking this drug.

Avoid pregnancy while taking megestrol. There’s a chance this drug could cause birth defects if it’s taken at the time of conception or during pregnancy. If there’s any chance of pregnancy, check with your doctor about what kinds of birth control you can use.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • Fluid retention
  • Swelling in hands, feet, legs
  • Increased appetite
  • Weight gain

Less common

  • Mental depression
  • Rash
  • Vaginal bleeding or spotting during treatment
  • Vaginal bleeding during or after treatment is stopped*
  • Headache
  • Diarrhea
  • Decreased sexual desire and sometimes impotence in men


  • Nausea
  • Breast tenderness
  • High blood sugar*
  • High calcium levels in those with breast cancer that has spread to bones*
  • Adrenal glands stop working well, causing weakness, nausea, vomiting, dizziness*
  • Blood clots with redness or mild swelling of legs or arms, pain in leg or calf, shortness of breath, pain in the chest, trouble moving or speaking*

*See “Precautions” section for more detailed information.

There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved before 1984 (FDA cannot verify dates of drugs approved before 1984.)

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 12/02/2014
Last Revised: 12/02/2014