Gynecomastia is a benign (noncancerous) overdevelopment of the male breast due to a change in the ratio of estrogen and testosterone levels. While the dominant hormone in men is testosterone, estrogen is still present, although in lower amounts than testosterone. When estrogen levels increase or testosterone levels decrease, the result is growth or swelling of the glandular tissue in one or both male breasts.

Glandular tissue, one of three different types of tissue found in the breast, includes the milk ducts and glands. Fibrous tissue supports the breast. Fat fills the spaces between the other tissues. (It is the amount of fat in the breast that gives the breast its size. Therefore, overweight men may have the appearance of breasts due to the distribution of fat in the chest.)

When Is Gynecomastia Likely to Occur?

Gynecomastia may occur during the following life stages:

  • In newborns, gynecomastia is due to residual levels of estrogen from the mother. Breast development in babies tends to gradually stop by 6 months of age.
  • In teen boys, gynecomastia is caused by the hormone changes of puberty (called pubertal gynecomastia), or drug and/or alcohol use. Breast development in teen boys usually stops within 6 months to 2 years.
  • In adult men, gynecomastia may be the results of declining testosterone levels with aging, a medical condition, medications, or drug and alcohol use.

What Causes Gynecomastia?

Gynecomastia has many causes, including the following:

  • Medical conditions, including cancer, cirrhosis of the liver, overactive thyroid, hypogonadism (reduced functioning of the testes), kidney failure, malnutrition, or benign tumor of the testes, adrenal glands, or pituitary gland;
  • Hormonal imbalance due to normal aging
  • Medications

    -Steroids, such as prednisone or dexamethasone
    -Stomach acid-reducing medications, such as cimetidine (Tagamet)
    -Anti-seizure medications, such as Dilantin;
    -Heart medications, such as digitalis, calcium channel blockers (for example, amlodipine), and anti-arrythmics (for example, amiodarone)
    -Chemotherapy drugs
    -Anti-androgen medications used to treat an enlarged prostate or prostate cancer (for example, flutamide, cyproterone, and spironolactone)
    -Medications used in the treatment of AIDS
    -Anti-anxiety and anti-depression medications, for example diazepam (Valium) and tricyclic antidepressants (such as amitriptyline and imipramine).

  • Street drugs, including alcohol, amphetamines, marijuana, heroin, and methadone
  • Herbals (found in aromatherapy, lotions, shampoos, and soaps), including tea tree and lavender

Important Note: Do not stop any prescribed medication without first consulting with your health care provider.

What Are the Symptoms?

Although gynecomastia is benign (noncancerous), development of breasts in men can cause embarrassment and emotional distress, especially in teenage boys. Additionally, men and boys may notice
  • A rubbery or firm lump at least 0.5 cm (5 mm) in diameter usually underlying the nipple.
  • Breast pain or tenderness

How Is It Diagnosed?

Gynecomastia can usually be diagnosed by a physical exam and medical history. Blood tests may be ordered, as well as a mammogram and/or breast ultrasound. A biopsy may be performed to rule out a more serious problem, such as breast cancer.

Any man or teenage boy who finds a breast lump should let his doctor know, especially if the lump is hard to the touch and fixed to the chest wall or skin, or if there is a history of breast cancer in his blood-related family members.

What Is the Treatment and Management?

Gynecomastia in babies and teen boys normally does not require treatment and will usually resolve on its own. If the gynecomastia is caused by a medication or drug and/or alcohol abuse, stopping the medication or drug use will often resolve the condition. If it is caused by an underlying medical problem, treating the medical problem may resolve the gynecomastia. If the gynecomastia is caused by low testosterone or high estrogen levels, hormonal treatment may be recommended. Surgery may be an option for some men if other treatments are unsuccessful or when gynecomastia in a teen boy does not go away after 2 years and it causes substantial emotional distress.