Gynecomastia is overdevelopment of the male breast. In response to too much
estrogen (a female hormone) or too little
testosterone (a male hormone), the glandular tissue of the breast swells and forms a breast bud (enlarged breast). Gynecomastia can occur in babies, teen boys, and older men.
What causes gynecomastia?
In newborns, gynecomastia
is caused by estrogen from the mother. Breast buds are common in baby boys. Breast buds tend to
go away gradually by 6 months of age, but they can last longer in some babies.
In preteen boys, gynecomastia can also be caused by an estrogen-producing tumor.
Breast buds are common during puberty. The buds may
last up to 2 years, but they tend to go away within the first year.
In teen boys, gynecomastia is caused by the hormonal changes of
puberty. Gynecomastia occurs in many boys during early puberty to middle
puberty. It usually goes away within 6 months to 2 years.
In adult males, gynecomastia is usually caused by another
condition, such as liver or lung cancer,
cirrhosis of the liver, overactive thyroid, or by
hormone problems, such as cancer of the
adrenal glands, or testicles. Alcohol, marijuana,
methamphetamine, and heroin use also may cause gynecomastia.
of certain medicines may also cause gynecomastia, including:
Steroids, such as prednisone or dexamethasone.
Medicines used to treat ulcers (such as cimetidine).
Medicines used to treat epilepsy (such as phenytoin
Digitalis and other heart medicines.
Chemotherapy drugs, especially alkylating agents, a
family of anticancer drugs that interfere with cell
DNA and inhibit cancer cell growth.
Antiandrogen drugs (such as flutamide, cyproterone, and
Antianxiety and antidepressant medicines (such as diazepam
[Valium] and tricyclic antidepressants).
What are the symptoms?
In addition to having
enlarged breasts, men or boys with gynecomastia may notice their breasts feel
rubbery or firm. Boys may have a breast bud on one or both sides about the size
of a nickel or quarter. Breast buds are common in adolescent boys
during puberty. They may last up to 2 years, but they tend to go away within
the first year.
How is gynecomastia diagnosed?
usually be diagnosed from a physical exam 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, a biopsy may be done to rule out other
Any man who finds a one-sided breast lump should let his
doctor know if he has close relatives who have had breast cancer (mother,
sister, or daughter). If there is any concern about cancer, a lump can be
checked with a biopsy or surgery.
How is it treated?
Gynecomastia in babies and
teens normally does not require treatment and will usually go away on its own.
If it is caused by medicine or disease, stopping the medicine or treating the disease
will often cure the gynecomastia. If it is caused by a lack of testosterone and
increase in estrogen, hormonal treatment may be prescribed. Surgery may be a choice for some men if other treatments have not worked.
How this information was developed to help you make better health decisions.