Gynecomastia is an overdevelopment of the male breast.

The glandular tissue of the breast swells, usually in response to an excess of the female hormone estrogen or lack of the male hormone testosterone.

Causes of Gynecomastia

In teen boys, gynecomastia changes are caused by the hormonal changes of puberty. In adult males, it is often caused by hormonal changes of aging, but it can also be caused by other conditions, such as medications, cancer, cirrhosis of the liver, overactive thyroid, or hormone problems that can occur with malfunctioning pituitary and adrenal glands. Alcohol, marijuana, methamphetamine, and heroin use also may cause gynecomastia.

Symptoms of Gynecomastia

Symptoms include enlarged breast tissue sometimes with pain and tenderness as well as breasts that can feel rubbery or firm.


Gynecomastia can usually be diagnosed from a physical examination and medical history. In most cases, tests are not necessary. But if the breast lump is unusually large, one sided, tender, or hard and fixed, imaging studies and a biopsy may be done to rule out cancer.

Any man who finds a one-sided breast lump should let his doctor know if he has a close relative (mother, sister, daughter) who has had breast cancer.

Gynecomastia in Teens

Gynecomastia in teens normally does not need any treatment and may go away on its own. If caused by medicine or disease, stopping the medicine or treating the disease will often cure the gynecomastia. If caused by a lack of testosterone and increase in estrogen, hormonal treatment may be prescribed. The breast tissue can be removed for continued pain or for cosmetic reasons.