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 level
Rare causes include:
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) or bicalutamide
- Radiation treatment of the testicles
- HIV/AIDS medicines
- Corticosteroids and anabolic steroids
- Estrogen (including those in soy products)
- 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:
Men who have enlarged breasts may have an increased risk for breast cancer. 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
The condition may occur in one or both breasts. It begins as a small lump beneath the nipple, which may be tender. One breast may be larger than the other.
Enlarged breasts in males are usually harmless, but may cause embarrassment for some men.
Some newborns may have breast development along with a milky discharge (galactorrhea). This condition usually lasts for a couple of weeks. In rare cases, it may last until the child is 2 years old.
When abnormally large breasts develop in males, it is called gynecomastia. It is due to the excess growth of breast tissue, not excess fat tissue.
For swollen breasts that are tender, applying cold compresses may help. Ask your health care provider if it's OK to take pain relievers.
Other tips include:
- Stop taking all recreational drugs, such as marijuana
- Stop taking all nutritional supplements or any drugs you are taking for bodybuilding
What to Expect at Your Office Visit
Your provider will take a medical history and perform a physical examination.
You may not need any tests, but the following tests may be done to rule out certain diseases:
Often no treatment is needed. Breast growth in newborns and young boys often goes away on its own.
If a medical condition is causing the problem, your provider will treat that condition.
Your provider will talk with you about medicines or substances that may cause breast growth. Stopping their use or changing medicines will make the problem go away. DO NOT stop taking any medicines before talking to your provider.
Breast growth that is extreme, uneven, or does not go away may be embarrassing. Treatments that may be used in rare situations are:
- Hormone treatment that blocks the effects of estrogens
- Breast reduction surgery or liposuction
When to Contact a Medical Professional
Call your provider if:
- You have recent swelling, pain, or enlargement in one or both breasts
- There is dark or bloody discharge from the nipples
- There is a skin sore or ulcer over the breast
- A breast lump feels hard or firm
If your son has breast growth but has not yet reached puberty, have it checked by a provider.
Ali O, Donohoue PA. Gynecomastia. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 585.
Anawalt BD. Gynecomastia. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 140.
Sansone A, Romanelli F, Sansone M, Lenzi A, Di Liugi L. Gynecomastia and hormones. Endocrine. Epub 2016 May 4. PMID: 27145756