What Causes Gynecomastia? Understanding the Most Common Reason for Male Breast Enlargement

Gynecomastia, or "Gyno," is the medical term for enlargement of male breast tissue and is a surprisingly common condition that affects men across various stages of life. Though often harmless, it can be emotionally distressing, physically uncomfortable and impact confidence. Understanding what causes gynecomastia, when it may resolve on its own or not, and how it can be treated is the first step toward managing it effectively.

What Is Gynecomastia?

Gynecomastia is the benign overdevelopment of glandular breast tissue in males, typically due to an imbalance between estrogen and testosterone levels. This is not the same as pseudogynecomastia, which refers to fat accumulation without true glandular growth.

Gynecomastia can affect one or both sides and may be symmetrical or asymmetrical. It is not usually dangerous, but it can be uncomfortable—physically and emotionally.

What are the symptoms of Gynecomastia?

• Enlarged, rubbery or firm mass beneath the nipple
• Puffy appearing nipple
• Tenderness or sensitivity in the breast area
• Swelling of one or both breasts
• Slight asymmetry where one side may be larger than the other
• Usually no nipple discharge or skin changes
• Many patients report wearing compression shirts under clothing to hide the appearance and avoid taking off their shirts in public or at the beach.

When and Why Does Gynecomastia Occur?

Gynecomastia can affect men of all ages, but it tends to appear at specific life stages:

1. Infancy

• Newborn babies have breast development and leak a milk-like fluid from their nipples — regardless of sex.
• Caused by estrogen passed from mom to the baby during pregnancy.
• Affects up to 60–90% of newborn males.
• This breast development usually resolves on its own within a few weeks after birth

2. Puberty or Adolescence (Ages 12–17)

• Very common due to the natural hormonal surge and imbalance during puberty.
• Affects up to 65% of adolescent boys.
• Typically resolves on its own within 6 months to 2 years.

3. Early to Mid-Adulthood (Ages 20s–40s)

• Often related to specific medications, anabolic steroids, or certain drug use

4. Older Men (Ages 50+)

• Due to decreasing testosterone, increased conversion of testosterone to estrogen, or other medical conditions.

What Causes Gynecomastia?

While hormonal imbalance (typically through an increase in estrogen or a decrease in testosterone) is often the root cause, several external factors can contribute:

Medications

A number of prescription and over-the-counter drugs are associated with gynecomastia. These generally contribute to high levels of certain hormones or low levels of other hormones including testosterone, estrogen and prolactin.

Anti-androgen medications

Androgens are a category of hormones that include testosterone and dihydrotestosterone (DHT). Androgens play many roles in the body, including blocking the effects of estrogen.

However, some medications interfere with androgens like testosterone and DHT. When this happens, they’re not able to block estrogen’s effects as well.

• Anti-androgens (for prostate issues or hair loss): fineasteride, dutasteride, flutamide
• Certain antidepressants, anti-anxiety, and anti-psychotic medications: Amitriptyline (Elavil), doxepin (Sinequan), imipramine (Tofranil), sertraline (Zoloft), duloxetine (Cymbalta), bupropion (Wellbutrin), diazepam (Valium), olanzapine (Zyprexa), resperidone (Risperdal), haloperidol (Haldol)
• Anabolic steroids
• Heart medications: Nifedipine, diltiazem, amlodipine, digoxin
• Ulcer medications: Cimetidine
• HIV antiretroviral medications: efavirenz

Recreational Drugs & Supplements

• Alcohol
• Cannabis (marijuana)
• Amphetamines
• Opioids
• Herbal products containing phytoestrogens (e.g., tea tree oil, lavender)
  

Medical Conditions

• Testicular tumors or injury
• Hyperthyroidism
• Liver or kidney disease
• Obesity, which increases aromatase activity (converts testosterone to estrogen)
• Klinefelter syndrome (a rare chromosomal disorder)

Do You Need Imaging or Labs?

Often, no. For healthy adolescents and adults with a classic presentation and no red flags, no further testing is needed. However, imaging or labs may be recommended if:

• There's a hard stuck down mass that is not directly under the nipple
• There’s nipple discharge or skin changes over the mass
• A testicular mass is also present
• Blood tests may be ordered to evaluate hormone levels, thyroid function, liver/kidney function, and rule out underlying causes

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How Is Gynecomastia Treated?

1. Observation

In adolescents and early cases, we often recommend a “wait and see” approach:

• Monitor for 6–12 months
• Avoid exacerbating medications/substances
• Lifestyle modifications: weight loss, improved fitness

2. Medical Therapy

Occasionally, medications like tamoxifen or raloxifene (selective estrogen receptor modulators) may help in early or painful cases. These are off-label and used selectively.

3. Surgical Treatment

When gynecomastia is long-standing, symptomatic, or emotionally distressing, surgery may be the best option:

• Gynecomastia surgery (male breast reduction) involves:
  • Liposuction for fat removal
  • Gland excision through a small incision (often a half-moon incision around around the areola), which is sent to the pathology lab to be checked under the microscope
  • Skin tightening or skin excision in more advanced cases

This can be done awake in the office with numbing medication or asleep at a surgery center. Results are typically permanent, and patients often experience improved confidence and body image.

Will CoolSculpting or Kybella work?

Generally, no they will not work for gynecomastia because it is often due to enlarged breast tissue not fat and may cause more inflammation and scar tissue in the area.

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Considering treatment for gynecomastia?

At Metropolitan Plastic Surgery, Dr. Aimé provides expert, compassionate care for men of all ages experiencing gynecomastia. From non-surgical guidance to state-of-the-art male chest contouring, you’ll get a personalized plan based on your goals and needs.

📞 Schedule a consultation today to explore your options with confidence.