Causes of Man Boobs

Men will develop breasts when there is an imbalance of testosterone and estrogen. There are many known reasons for the imbalance, but as much as 25% of cases remain unknown. Some of the known causes are medications, heredity, street drugs, alcohol, herbal products, and some health issues. It is not known why some men develop man boobs and others do not, and many have only one breast affected. Estrogen produces female characteristics, and when estrogen levels increase, it will trigger breast development. Along with enlarged breasts, most men with man boobs will have breast tenderness, and some may have nipple discharge. Men should be aware of the possible causes of gynecomastia and avoid them if possible.

What causes Gynecomastia?

Common Causes

  • Medications

    Some prescription medications contribute to male breast development by increasing prolactin secretion in the pituitary gland. In addition, some meds are known to create an imbalance by decreasing testosterone levels. Some known drugs that may have breast enlargement as a side effect are antibiotics, antidepressants, ulcer medication, Aids treatments, blood pressure drugs, valium and other sleep aids. Not all of these drugs will cause gynecomastia for all men, sometimes changing a prescription may resolve breast growth, but it could take many months to 2 years.

    Finasteride (Propecia) the drug used for the treatment of androgenetic alopecia (hair loss) has been known to cause man boobs. However, the incidence is very low between 4 to 10 out of 1,000 users, but men should be aware of the possible side effect and note if they should start feeling any breast tenderness or pain, and notify their doctor. If the medication is stopped early, it most likely will be reversed. It is more likely to develop in obese and older men and can be bilateral or unilateral in development.

    There have been thousands of lawsuits filed against Janssen Pharmaceuticals and its parent company, Johnson and Johnson, for their antipsychotic drug, Risperdal, due to improper marketing of the medication. It has been proven to cause gynecomastia in men and even children. Risperdal has been in litigation for years and to date has been ordered to pay one of the largest settlements for fraud in health care in United States history. Johnson and Johnson have paid more than $2 billion in settlements and penalties.

Anabolic Steroid Use

Steroids are known to promote muscle growth but will also reduce production of testosterone, leading to breast development. Many bodybuilders and weightlifters, who use steroids, struggle with moobs.

Recreational Drugs

Amphetamines, marijuana, heroin, cocaine, and methadone, affect the androgen receptors.

Alcohol Abuse

The body has a hard time getting rid of estrogen and phytoestrogen that are present in beer and hard liquor when consumed in large amounts.


Liver damage may hinder the production of testosterone.

Kidney Damage

Hemodialysis can lead to significant hormonal changes.

Herbal Products and Supplements

Lavender oil, tea tree oil, some shampoos, lotions, and soaps.


When the ratio of muscle to fat becomes unbalanced; the excessive fat stimulates the production of estrogen leading to breast development.


Male babies are exposed to high levels of estrogen while in the womb. Many are born with some breast tissue, but most resolve in a few weeks after birth.


60% or more adolescent males develop breast tissue as they go through puberty, but usually, within a few months to 2 years, it will dissipate. However, for some, the breast tissue may be permanent.


After the age of 50, many men develop medical and hormonal conditions due to low testosterone (low-T), including diabetes, obesity and gynecomastia.


If gynecomastia runs in a family it is possible it will get passed down, but it may be only temporary and disappear after puberty, but for some, it will be permanent.

Uncommon Causes


If a man is not getting enough nutrients it may affect his testosterone level. Once a normal diet is resumed he may develop man boobs. The medical term for this phenomenon is “re-feeding gynecomastia,” it was noted when World War II prisoners of war returned to a regular diet after their release. For most men, their breasts returned to normal in 1 to 2 years.

Smoking and Cancer

Cigarette smoking is a known cause of cancer. Various types of cancer including lung cancer and testicular cancer may cause moobs.


And other treatments for cancer.

Graves’ Disease

An immune system disorder that causes overproduction of thyroid hormones.

Klinefelter’s Syndrome

A condition where a man has an extra X chromosome resulting in small testes and enlarged breasts.

Hodgkin’s Lymphoma

A cancer of the lymphatic system that is part of the immune system.

Breast Cancer in Men

Men with gynecomastia may have a slightly higher risk of developing breast cancer due to the higher ratio of estrogen to testosterone in their body. Man boobs are common for men, but breast cancer for men is very rare. There are approximately 2,000 new cases of breast cancer diagnosed in men each year and of those about 400 will die. Breast cancer for men is usually more serious than for women because typically it is not detected as early. It is recommended that men perform self-examinations of their breast periodically and report any changes or lumps to their doctor.

Foods That are High in Estrogen

Estrogen in plant form is not the same as human estrogen but is very similar on a molecular level and may have the same effect on the human body. It is still debated if estrogen in the diet is enough to cause man boobs, but there is compelling evidence that it is possible and many believe that it is probable. Men struggling with breast development may want to evaluate their diet. Soy is a potent source of plant estrogen. However, flax seeds have 265% more phytoestrogens than soybeans. Possibly worse than flax seeds is milk. Estrogen from cows is identical to human estrogen. Protein drinks made with whey or casein are derived from milk. Plant-based, soy free protein powders would be the best choice. Protein bars may be worse than the powders as many are made with whey and flax seeds.

What Your Surgeon Will Want to Know

At your first consultation, your gynecomastia specialist will inquire about your medical history and do a physical exam. In trying to determine the cause of your man boobs, you may be asked some of the following questions:

  • When did your breasts develop?
  • Do you have breast tenderness?
  • Do you have any nipple discharge?
  • Do you notice changes in your breasts when your weight fluctuates?
  • Are you comfortable removing your shirt in public?
  • Do any of your family members have gynecomastia or breast cancer?
  • How much alcohol do you consume?
  • Do you take any prescription medications?
  • Do you use any recreational drugs?
  • What supplements do you take?
  • Do you use soy or flaxseeds in your diet?
  • Do you drink milk?
  • Do you use steroids?
  • Do you have Klinefelter’s Syndrome?
  • Do you have Hodgkin’s Lymphoma?
  • Do you have Grave’s Disease?

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Before & After Photos