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What is gynecomastia?

Gynecomastia is an enlargement or swelling of breast tissue in males. It can affect one or both breasts.

What causes gynecomastia?

Gynecomastia is most commonly caused by an imbalance between the hormones estrogen and testosterone. Estrogen controls female traits, including breast growth. Testosterone controls male traits, such as muscle mass and body hair. Although each of these hormones produces the usual traits seen in males and females, males produce a small amount of estrogen and females produce a small amount of testosterone. Male estrogen levels that are too high or are out of balance with testosterone levels cause gynecomastia.

Gynecomastia occurs naturally at different times in a male’s life. These phases are:

  • After birth. Newborn boys are still under the effects of the estrogen they received from their mothers while developing in the womb. More than half of newborn males are born with enlarged breasts. The gynecomastia goes away within two to three weeks after birth.
  • At puberty. Hormone levels are changing during puberty (usually 12 to 14 years of age). Breast enlargement usually goes away six months to two years after the start of puberty.
  • At mid-life and beyond. Breast enlargement often peaks in men between the ages of 50 and 80. About one in four men in this age range have breast enlargement.

There are many other conditions that can cause gynecomastia. These include:

  • Obesity
  • Lack of proper nutrition
  • Tumors in the testicles or adrenal glands
  • Liver disease
  • Hyperthyroidism
  • Hypoandrogenism
  • Hypogonadism
  • Kidney failure

Certain drugs can also cause gynecomastia, including:

  • Anabolic steroids for improved athletic performance
  • Estrogens
  • Finasteride (Proscar®, Propecia®) for enlarged prostate
  • Spironolactone (Aldactone®), digoxin (Lanoxin®), amiodarone (Cordarone®), and calcium channel blockers
  • Cimetidine (Tagamet®) and proton pump inhibitors for heartburn
  • Diazepam (Valium®) for anxiety
  • Ketoconazole (Nizoral®) for fungal infections
  • Metronidazole (Flagyl®) for bacterial infections
  • Human chorionic gonadotropin for fertility problems
  • Amphetamines, marijuana, heroin, methadone (“street” drugs) and alcohol