Updated June 29, 2015.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Megace (megestrol acetate) is typically given to people who are very sick with breast cancer,  endometrial cancer or AIDS.  This drug is given to boost appetite and weight gain. In those patients who are very sick and prescribed Megace, this drug's hormone effects can be soothing and cause an increase in well being, too. 

Sometimes people who are older and underweight are prescribed Megace, but this drug's efficacy in an elderly population is unproven.

  Most of the research on Megace involves those with cancer or AIDS.

Megace is an endocrine-metabolic agent and synthetic hormone.  Because Megace is a synthetic hormone, it has a variety of adverse effects which involve many organ systems spanning the entire body.

 

Mechanism of action

 

Megace or megestrol acentate is a synthetic progestin that has antiestrogen properties and may effect the endometrium or lining of the uterus.  Specifically, Megace interferes with the estrogen-receptor cycle and is thought to effect the pituitary gland in the brain (pictured in this article).  The pituitary gland secretes hormones that effect your muscles, kidneys and various organs.   Some experts believe that Megace boosts appetite through its effect on body metabolism (catabolic cytokines).

 

Megace clinical indications

 

Megace is given to:

• relieve suffering caused by endometrial cancer or breast cancer;
• increase appetite and stop weight loss in people with AIDS and cancer (cachexia)
• boost appetite in prostate cancer

• boost mood in people with AIDS and cancer
• provide hormone therapy for endometrial and breast cancer

As mentioned earlier, there is no evidence-based support for the use of Megace as treatment for appetite loss in older people.

 

Megace adverse effects

 

Megace has no interactions with other drugs.  However, Megace has wide-ranging clinical actions and can interfere with health and well being well being in various ways, In the following list, possible adverse effects of Megace are followed by estimated prevalence.

• hypertension (4 percent to 8 percent)
• chest pain (1 percent to 3 percent)
• palpitations (1 percent to 3 percent)
• headache (3 percent to 10 percent)
• insomnia (1 percent to 6 percent)
• depression (1 percent to 3 percent)
• neuropathy or nerve weakness (1 percent 3 percent)
• skin rash (6 percent to 12 percent)
• pruritis or skin itch (1 percent to 3 percent)
• hyperglycemia or high sugars (6 percent)
• breast enlargement or gynecomastia (1 percent to 3 percent)
• diarrhea (10 percent and equal to placebo)
• constipation (1 percent to 3 percent)
• impotence (4 percent to 14 percent)
• urinary incontinence (1 percent to 3 percent)
• infection (1 percent to 3 percent)
• eye problems (1 percent to 3 percent)
• cough (1 percent to 3 percent)
• fever (1 percent to 6 percent)
• infection (1 percent to 3 percent)
• enlarged liver or hepatomegaly (1 percent to 3 percent)

Of note, Megace should not be taken during pregnancy and can harm the fetus.

I included so many items in this list to prove a point: Megace is a hormone, and many people who take hormones will experience some negative side effects. Hormone therapy should be carefully considered and can sometimes exacerbate heart disease or cause severe depression.  For this reason, Megace is s drug best reserved for people in end-stage care not elderly people who need to gain weight.

If you're taking Megace and experience chest pain, nausea, vomiting, frequent urination, leg pain, or anything else that makes you feel terrible, make sure to discontinue use of the medication and see a physician immediately.  If need be, call emergency services.

Megace is available in oral form as both a suspension and a pill.  There are cheaper generic versions of this medication available. 

Depending on provider and patient worldview, one alternative to Megace in elderly patients is medical marijuana.

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Family Practice Examination & Board Review, Third Edition by M Graber and J Wilber published in 2012.

Mosby's Drug References for Health Professionals, Second Edition published in 2010.</sub>