Gynecomastia Causes

Gynaecomastia (sometimes referred to as ‘man boobs’) is a common condition that causes boys’ and men’s breasts to swell and become larger than normal. It is most common in teenage boys and older men.

Gynecomastia is a condition in which the breasts become enlarged in boys or men, sometimes causing discomfort or nipple tenderness. It is usually the result of a hormonal imbalance and typically occurs during infancy, adolescence, or mid- to late-life.

The condition often goes away on its own, but treatments are available for severe or persistent cases.

When gynecomastia is the result of an underlying health problem, treatment of that problem usually improves the gynecomastia as well.

Up to 70 percent of boys in early to mid-puberty experience gynecomastia because of the normal hormonal changes that occur during puberty.

Gynecomastia is also common among middle-aged and elderly men. In this population, up to 65 percent of men are affected

Common causes of Gynecomastia

Although people tend to think of androgens as “male hormones” and estrogens as “female hormones,” people of both sexes produce both types of hormones.

In males, androgens are by far the predominant hormone, but small amounts of estrogen are also present. Gynecomastia can happen when the balance shifts, with an increase in estrogen or decrease in androgens.

This can occur because of expected hormonal changes during puberty or aging, or because of the use of certain drugs or herbal products.

The most common causes of gynecomastia in adult men include:

  • Pubertal gynecomastia that does not resolve — 25 percent
  • Drugs — 10 to 25 percent
  • Unknown causes (idiopathic) — 25 percent
  • Puberty — Gynecomastia that occurs during puberty usually resolves without treatment within six months to two years.

The condition sometimes develops between ages 10 and 12 years, and most commonly occurs between ages 13 and 14. It is uncommon for the condition to persist beyond age 17.

  • Drugs — Many drugs have been associated with gynecomastia, including:

1. Spironolactone (Aldactone), a drug used to treat heart failure, high blood pressure, and several other conditions.
2. Ketoconazole, a drug used to treat fungal infections.
3. Cimetidine (Tagamet), ranitidine (Zantac), and related drugs called H2-receptor blockers. These drugs are used to treat stomach ulcers and severe heartburn.

If gynecomastia is caused by one of the drugs you take, your healthcare provider may recommend that you stop using the drug or replace it with another drug that is less likely to cause the condition.

Gynecomastia occurs in up to 75 percent of men who take drugs called antiandrogens to treat prostate cancer.

While these men may not be able to stop or substitute their prostate cancer treatment, they may be able to take steps to prevent gynecomastia.

  • Herbal products — Gynecomastia in children has been associated with regular use of skin care products (lotions, soaps, and shampoos) containing tea tree oil and lavender oil.

These oils contain plant estrogens and can affect the body’s hormone balance. Gynecomastia usually resolves completely after stopping the products.

Soy products, such as soy milk, do not usually cause gynecomastia unless a large quantity is consumed.

  • Treatment for HIV/AIDS (HAART) — Men taking combination treatment for HIV/AIDS, called highly active antiretroviral therapy (HAART), sometimes develop enlarged breasts.

In most cases, this breast enlargement is due to fat redistribution, which is a side effect of the treatment. In some cases, though, true gynecomastia has been associated with HAART.

  • Unknown causes (idiopathic) — It is not always clear what causes gynecomastia during mid- to late-life. Still, as men age, blood testosterone levels decline and the hormone balance changes, favoring an increased level of estrogen.

These factors probably conspire to account for most cases of “idiopathic” gynecomastia

What are the signs of gynaecomastia?

Signs vary from a small amount of extra tissue around the nipples to more prominent breasts. It can affect one or both breasts.

Sometimes, the breast tissue can be tender or painful, but this isn’t always the case.
What causes gynaecomastia?

Gynaecomastia can have several causes.

Hormone imbalance

Gynaecomastia can be caused by an imbalance between the sex hormones testosterone and oestrogen. Oestrogen causes breast tissue to grow.

While all men produce some oestrogen, they usually have much higher levels of testosterone, which stops the oestrogen from causing breast tissue to grow.

If the balance of hormones in his body changes, this can cause a man’s breasts to grow. Sometimes, the cause of this imbalance is unknown.

The growth in breast tissue is not due to extra body fat from being overweight, so losing weight or doing more exercise will not improve the condition.

Newborn baby boys

Gynaecomastia can affect newborn baby boys because oestrogen passes through the placenta from the mother to the baby. This is temporary and will disappear a few weeks after the baby is born.


During puberty, boys’ hormone levels vary. If the level of testosterone drops, oestrogen can cause breast tissue to grow. Many teenage boys have some degree of breast enlargement.

Gynaecomastia at puberty usually clears up as boys get older and their hormone levels become more stable.

Older age

As men get older, they produce less testosterone. Also, older men tend to have more body fat, and this can cause more oestrogen to be produced.

These changes in hormone levels can lead to excess breast tissue growth.

Other causes

In rare cases, gynaecomastia can be caused by:

  • side effects of medication, such as anti-ulcer drugs or medication for heart disease
  • illegal drugs, such as cannabis or anabolic steroids
  • drinking too much alcohol
  • a health abnormality, such as kidney failure or liver disease
  • Klinefelter’s syndrome, a rare genetic disorder
  • lumps or infection in the testicles

Treatment for gynaecomastia

If you’re worried about breast tissue growth, see your GP.

If your GP thinks treatment is needed, there are two types of treatment for gynaecomastia:

  • surgery to remove the excess breast tissue
  • medication to adjust a hormone imbalance

Your GP can discuss the treatment options with you. Find out more about male breast reduction surgery.

Procedures such as breast reduction surgery are not usually available on the NHS unless there is a clear medical need for them.

For example, if you have had gynaecomastia for a long time, it has not responded to other treatments and it is causing you a lot of distress or pain, your GP may refer you to a plastic surgeon to discuss the possibility of surgery.

Always see your GP if the area is very painful or there is an obvious lump. Sometimes, the lump may need to be removed.

Gynaecomastia is not related to breast cancer but if worried about breast swelling, see a GP.


Gynecomastia in adolescent boys is usually caused by puberty-related hormonal changes and typically resolves on its own. In extreme or painful cases, a brief course of tamoxifen may be recommended.

Gynecomastia in adult men is usually caused by another underlying health problem or by the use of a drug. In such cases, treating the underlying condition or suspending the drug usually allows gynecomastia to resolve.

When the cause of gynecomastia cannot be identified, brief use of tamoxifen may be recommended.

Men who have had gynecomastia for more than one year do not typically benefit from the use of tamoxifen. For them, surgery to reduce the size of the breasts is an option.

Men with prostate cancer who undergo certain types of hormone treatment (eg, antiandrogen monotherapy) are at risk for developing gynecomastia.

Pre-treatment with radiation or taking a medication (tamoxifen) along with the antiandrogen are two options for preventing breast growth.

Source & More Info: and UpToDate



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