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Gynecomastia (gi ne co MAS tia) is excess growth of breast tissue in males. Usually, it is caused by an imbalance of estrogen and testosterone. This is known as physiologic gynecomastia.  Although estrogen is considered to be a female hormone, it is also needed in males for healthy bone development. When the small amount of breast tissue normally present in boys is exposed to rising levels of estrogen (typical during early puberty) breast enlargement may occur.

Rarely, gynecomastia can be caused by an underlying health condition. This is known as pathological gynecomastia. Causes for pathological gynecomastia include:

  • Certain medicines or other substances (such as marijuana)
  • Diseases affecting hormones
  • Tumors
  • Chromosomal disorders


Signs and symptoms of gynecomastia may include:

  • Swollen breast gland tissue
  • Breast tenderness
  • Nipple discharge
  • Swollen nipples
  • Psychological or emotional concerns

How Common Is Gynecomastia?

Temporary breast enlargement often happens to adolescent boys. This is a time when there are hormonal changes. Over half of all males between 12 and 16 who are going through puberty have some form of gynecomastia in one or both breasts. It is usually a temporary condition that flattens out in a few months to a few years.


  • Physiologic Gynecomastia - Depending on how long the breast enlargement lasts, it may be best to follow up at 6 to 12 month intervals to see if it improves on its own. In 90 percent of teenage boys, gynecomastia goes away without treatment in 2 to 3 years.
  • Pathological Gynecomastia - For the 10 percent who continue to have breast enlargement, surgical treatment may be considered if it does not go away on its own. Sometimes underlying conditions need to be treated. In these cases, the patient should be seen and treated by an endocrinologist.

Gynecomastia (PDF)

HH-I-455 11/19 | Copyright 2019, Nationwide Children’s Hospital