Fat Gain With Propecia

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Propecia is a drug used primarily to treat hair loss. Although generally safe for use in men, there can be side effects that vary from one person to another. One potential side effect, although somewhat rare, may be an increase in abdominal fat and overall weight gain.


Propecia is the brand name for the generic drug finasteride. For men with hair loss, Propecia may increase the number of scalp hairs but won’t increase the amount of body hair, according to Drugs.com. The hair growth only lasts for the duration the drug is taken and if stopped, the hair will be lost.


Propecia works by blocking the action of the 5-alpha-reductase enzyme. This enzyme changes testosterone to a different hormone, dihydroxytestosterone, which causes hair loss in males. The effects of the 5-alpha-reductase enzyme also cause prostate enlargement, but Propecia manipulates and lowers the androgen levels in the prostate gland to shrink the gland and to improve symptoms and urinary flow rate, reports Ray Sahelian, M.D., best-selling author of “Mind Boosters” and other books.

Expert Insight

A study at the Fred Hutchinson Cancer Research Center, Seattle, Washington, led by Y. Song, and published in the journal “Prostate” in February 2008, looked at the effects of body weight changes in participants in the Prostate Cancer Prevention Trial taking finasteride over seven years and how it related to a risk of prostate cancer. They found that although men on finasteride didn’t exhibit weight gain in general, those who did were at a higher risk for prostate cancer. They concluded that genetic characteristics or environmental exposures can affect finasteride outcomes on weight gain and prostate cancer.


Although few clinical trials of Propecia found fat gain to be a common side effect, a study at the University of Medical Sciences, Tabriz University, in Iran, reported in “BMC Clinical Pharmacology” in October 2006 that finasteride induced anxiety and depression in human subjects. Since depression is associated with a reduced interest in exercise and an increase in food consumption in some people, it’s possible that weight and fat gains noticed by men on Propecia could be tied to this side effect. If you are taking Propecia and notice weight gain or depressive symptoms, you should check with your doctor about lifestyle changes or switching to another medication.


Propecia is not recommended for children or women who are pregnant or trying to get pregnant. Finasteride can be absorbed through the skin and cause birth defects in male babies, so it’s important that even if a woman touches the drug, she should be careful to wash the area immediately, reports Drugs.com. Finasteride can also change breast tissue, resulting in lumps, pain, tenderness or enlargement, and may affect the results of the prostate specific antigen, or PSA, test that is used to detect prostate cancer. Common side effects include chills, dizziness and a decrease in libido, ejaculate and the inability to have or keep an erection.