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What is Gynaecomastia?
Gynaecomastia is a common condition in which there is an increase in the amount of breast tissue in boys or men.
Gynaecomastia is quite common but rarely talked about because some men, and
particularly boys, find it embarrassing.
Some men and boys have fat on their chests that makes it look like they have breasts. This condition is called “false gynaecomastia”. It is not the same thing as gynaecomastia.
Symptoms of Gynaecomastia
Gynaecomastia can affect one or both breasts.
Gynecomastia can appear as a button-like or disk-like area or swelling of firm tissue under the nipple and areola. The area can be tender to touch or painful.
What causes Gynaecomastia?
Gynaecomastia may be caused by changes in the balance of two hormones, oestrogen and testosterone, this can happen at puberty or as part of aging in some cases, gynaecomastia may also be caused by prescription drugs, over-the-counter medicines or illegal drugs.
Hormone imbalance
Gynaecomastia can be caused by an imbalance between the sex hormones testosterone and oestrogen. Oestrogen causes breast tissue to grow. 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 the body changes, this can cause a man's breasts to grow.
Sometimes, the cause of this imbalance is unknown.
Puberty
Boys also have higher levels of oestrogen during puberty but, by the end of their teenage years, they usually have much higher levels of the hormone testosterone. This stops the effect of oestrogen on breast tissue, and the breast usually flattens out.
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. In addition, they tend to have more body fat, which causes oestrogen to be produced. The combination of an increase in oestrogen and reduced testosterone levels can lead to excess breast tissue growth.
Obesity
The more fat cells a person has in their body, the more oestrogen they produce. This in turn can make breast tissue grow. A well-balanced diet and exercise are important in maintaining a healthy weight.
Drugs and Medicines
Some drugs (both illegal and prescription) can cause gynaecomastia. This may be because they contain oestrogen, which increases the level of the hormone in the body. Or, more commonly, the drug may have an oestrogen-like effect. Some drugs block testosterone production altogether, reducing the level of testosterone in the body.
Cannabis is a drug thought to cause a hormone imbalance and therefore may be a reason for gynaecomastia developing.
Several other types of medicines can change the hormone balance in the body. Those
taken for high blood pressure or heart conditions, some psychiatric conditions, stomach ulcers, some cancer therapies, as well as anabolic steroids, can all be a cause of gynaecomastia.
Alcohol
Drinking large quantities of alcohol stimulates the liver and can create a hormone
imbalance. Circulating testosterone is reduced, but oestrogen levels rise as the liver stops breaking down the circulating oestrogen.
Other causes
- Klinefelter syndrome (a rare genetic disorder)
- Lumps or infection in the testicles
How is gynaecomastia diagnosed?
Your GP will refer you to a breast clinic, where the specialist Doctor will examine you and give advice on any treatment needed. You may also have a breast ultrasound requested which will be performed at a subsequent appointment.
Treatment and follow-up
In most cases you won’t need any treatment or follow-up if you have gynaecomastia.
However, it’s important to go back to your GP if the breast(s) grows larger or becomes more painful, or if you have any new symptoms.
For some people, removing the cause of the gynaecomastia (such as changing medicines, reducing excess body fat or reducing alcohol intake) is all that’s needed to shrink the enlarged breast tissue.
Occasionally some people may need to have drug treatments or, very rarely, surgery.
Contact us
If you have any queries relating to this information, please contact the Radiology service.
About this information
Service:
Radiology
Reference:
PILS-MAMM.18
Approval date:
29 April 2025
Review date:
29 April 2028
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.