Megestrol acetate

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Megestrol acetate


Generic NameBrand Name
megestrol acetateMegace

Megestrol is available as 40 mg and 160 mg tablets. The usual daily dose is 160 mg. You can take it all at once or spread it out through the day.

How It Works

Megestrol is a man-made progestin similar to the hormone progesterone. Experts do not completely understand how megestrol works, but most believe that it interferes with receptors that help breast cancer grow and spread.

Why It Is Used

Megestrol can be used to treat metastatic or recurrent breast cancer after tamoxifen treatment. It can also be used when tamoxifen is not effective.

Megestrol is used mainly to treat breast cancer. It is also sometimes used to treat endometrial cancer and prostate cancer.

Megestrol can be used as an appetite stimulant for people experiencing loss of appetite and weight loss because of advanced cancer.

How Well It Works

Megestrol is a second- or third-choice treatment for metastatic or recurrent breast cancer. This is because it has significant side effects. It is known to help control cancer and extend life. But compared to aromatase inhibitors, megestrol is not as likely to be effective.2

Megestrol may help relieve bone pain, and it can improve appetite and weight gain.1

Side Effects

Possible side effects of megestrol include:

  • Nausea.
  • Weight gain.
  • Fluid collection in the feet and ankles (edema).
  • Vaginal bleeding.

Megestrol raises the risk of dangerous blood clots (deep vein thrombosis). This risk is even higher for women who smoke or who have had blood clots before.3

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Megestrol should be used only under the supervision of a medical oncologist.

Megestrol can cause birth defects. Do not use this medicine if you are pregnant or wish to become pregnant.

If you have diabetes, you may need to adjust your insulin dose while you are being treated with megestrol. You will need regular appointments with your doctor to monitor your insulin levels.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Stebbing J, et al. (2007). Breast cancer (metastatic) , search date June 2006. Online version of BMJ Clinical Evidence:
  2. Hillner BE, Radice D (2001). Cost-effectiveness analysis of exemestane compared with megestrol in patients with advanced breast carcinoma. Cancer, 91(3): 484–489.
  3. Ellis MJ, et al. (2004). Treatment of metastatic breast cancer. In JR Harris et al., eds., Diseases of the Breast, 3rd ed., pp. 1101–1159. Philadelphia: Lippincott Williams and Wilkins.


By Healthwise Staff
Primary Medical Reviewer Joy Melnikow, MD, MPH - Family Medicine
Specialist Medical Reviewer Douglas A. Stewart, MD - Medical Oncology
Specialist Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Last Revised October 20, 2009

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