Normal hormone changes are the most common cause of breast development in newborns, boys, and men. There are other causes as well.
Breast enlargement is usually caused by an imbalance of estrogen (female hormone) and testosterone (male hormone). Males have both types of hormones in their body. Changes in the levels of these hormones, or in how the body uses or responds to these hormones can cause enlarged breasts in males.
In newborns, breast growth is caused by being exposed to estrogen from the mother. About half of boy babies are born with enlarged breasts, called breast buds. They usually go away in 2 to 6 months, but can last longer.
In preteens and teens, breast growth is caused by normal hormone changes that occur in puberty. More than half of boys develop breasts during puberty. Breast growth often goes away in about 6 months to 2 years.
In men, hormone changes due to aging can cause breast growth. This may occur more often in overweight men and in men age 50 and older.
Certain health problems can cause breast growth in adult men, including:
- Chronic liver disease
- Kidney failure and dialysis
- Low testosterone levels
Rare causes include:
- Genetic defects
- Overactive thyroid
MEDICINES AND MEDICAL TREATMENT
Some medicines and treatments that can cause breast growth in men include:
- Cancer chemotherapy
- Hormone treatment for prostate cancer, such as flutamide (Proscar), or for enlarged prostate, such as finasteride (Propecia)
- Radiation treatment of the testicles
- HIV medicines
- Anabolic steroids
- Heartburn and ulcer medicines, such as cimetidine (Tagamet) or proton pump inhibitors
- Anti-anxiety medicines, such as diazepam (Valium)
- Heart medicines, such as spironolactone (Aldactone), digoxin (Lanoxin), amiodarone, and calcium channel blockers
- Antifungal medicines, such as ketoconazole (Nizoral)
- Antibiotics such as metronidazole (Flagyl)
- Tricyclic antidepressants such as amitriptyline (Elavil)
- Herbals such as lavender, tea tree oil, and dong quai
DRUG AND ALCOHOL USE
Using certain substances can cause breast enlargement:
Breast cancer in men is rare. Signs that may suggest breast cancer include:
- One-sided breast growth
- Firm or hard breast lump that feels like it is attached to the tissue
- Skin sore over the breast
- Bloody discharge from the nipple