What Is Gynecomastia?

Gynaecomastia (also spelled gynecomastia) is the abnormal growth of breast tissue in people assigned male at birth (PAMAB). It is a common occurrence, especially in newborns, teenagers and older people, but due  of the  tendency to be embarrassed by it (especially among the teenage population) , gynecomastia can often stay untreated.1 Even though gynaecomastia itself is usually not life threatening,  there is a chance that the underlying cause can be malignant, so it needs to be checked and treated by a healthcare professional.2 


So what exactly is gynaecomastia? Often regarded as  ‘man boobs’, gynaecomastia can be described as the abnormal enlargement of the breast tissue in PAMAB. This enlargement can be seen on either or both breasts and sometimes it can only affect parts of the breast  rather than the whole organ. The enlargement can also be both soft or hard to touch but it is more common for it to be soft and less tender.2

Causes of gynecomastia

Although the two most common causes of gynaecomastia are hormonal imbalance and obesity, reasons such as old age, puberty, medicational side effects, drug use, alcoholism and various health problems could also be the underlying cause.2 

Gynaecomastia should not be confused with adipomastia, a condition that is very common in obesity, which is excess skin or fat tissue in the breast without hormonal imbalance. In adipomastia, skin and fat tissue around the breast are increased without the increase of size in glandular breast tissue, like it is in gynaecomastia.

 Both oestrogen and the androgens are produced by both people assigned female at birth (PAFAB) and PAMAB. Oestrogen is commonly associated with PAFAB and the androgens, a group of sex hormones that includes testosterone, are associated with PAMAB. These sex hormones regulate various endocrine systems in the human body and an increased ratio of oestrogen to androgens in the body is the primary reason behind gynaecomastia and thus any condition or medication that affects this hormonal balance causes enlarged breast tissue in men. 

Increased oestrogen is one of the ways this hormonal imbalance occurs. Tumours in organs such as testes, adrenal glands, pituitary glands and the lungs either directly or indirectly increase oestrogen levels. While rare genetic disorders such as Peutz-Jeghers syndrome and aromatase excess syndrome also cause oestrogen excess, obesity. Increased age can also be the underlying reason.3,4

Another way the oestrogen/androgen ratio is broken is due to an  androgen deficiency or androgen resistance. Pituitary gland plays a big role in this as hormones released from the pituitary gland controls  sex hormone secretion from the testes. As a result a rare genetic disease klinefelter syndrome,hypogonadotropic hypogonadism or any other disease that causes problems in hypothalamus or pituitary gland, will result in decreased androgen production. 

Problems in androgen receptors (also known as androgen insensitivity syndrome) can also play a role in androgen deficiency as the cells in the body will not be able to react to androgene even when hormone levels in the bloodstream are sufficient.3,4

There are some common medications and illegal drugs whose side effects can also lead to gynaecomastia due to disruption of the oestrogen/androgen ratio.2,5 

  • Birth control pills (oral contraceptives)
  • Types hypertension medications (calcium channel blockers) 
  • Heartburn medications (cimetidine) 
  • Antifungal medications (ketoconazole)  
  • Prostate medications (5α-reductase inhibitors) 
  • Anabolic steroids  (commonly used by bodybuilders)  
  • Excessive cannabis use 

There are also chronic diseases such as:6  

As it is with many medical conditions, gynaecomastia can naturally occur without any underlying medical condition. For example gynaecomastia in newborn babies is quite common and it is temporary. This happens because oestrogen passes from mother to the baby via the umbilical cord during pregnancy and sometimes the excess oestrogen hormone causes gynaecomastia in newborns. This type of gynaecomastia is temporary and should resolve within a few weeks of birth.7

Management and treatment for gynecomastia

Before jumping to any conclusions, gynaecomastia should be diagnosed by a medical professional, usually a  your general practitioner, who will make the diagnosis via examination and discuss the treatment options suitable for the individual. The reason is, as stated above, there could be malignant underlying conditions causing the gynaecomastia and these may need to be treated as well.

Gynaecomastia may resolve on its own within two years but if that's not the case, there are two main treatment options: which are medication or surgery.2 

Gynaecomastia is usually caused because of the imbalance of sex hormones. Medications such as selective oestrogen receptor modulators can help balance the hormone levels to stop and to reduce the swelling of breast tissue. If there is an underlying cause behind gynaecomastia, such as obesity, working towards solving that cause in conjunction with the hormonal medication treatment will help achieve a more sustainable prognosis.2,5

In some cases however, medication alone may not be enough to reduce the swelling of the breast tissue. This is when surgical removal of the breast tissue (in conjecture with liposuction) may be the only option, especially if gynaecomastia is causing physical or psychological distress to the affected individual. Psychological help can also be useful in order to combat the physiological stress caused by the condition.1,5


How common is gynecomastia?

Gynaecomastia is a very common condition in PAMAB  aged above 50 years. Affecting 35% of the male population, it is the most common benign medical condition of the breast tissue in PAMAB. Also around 70% of adolescent boys are expected to develop various levels of gynaecomastia during their puberty. Although three quarters of these are expected to resolve on their own within two years.4

Who is at risk of gynecomastia?

There are studies that suggest in recent years more new cases of gynaecomastia are being seen. There are various factors that could potentially be causing this. Increased use of anabolic steroids, increased exposure to chemicals and/or pesticides and increased use of cosmetic products have all been suggested as reasons behind the high prevalence, although none of these claims have been clinically proven so far.1

How can I prevent gynecomastia?

Prevention of gynaecomastia depends on the underlying reason behind the hormonal imbalance. In congenital conditions, management of the original disorder is the key to prevention, whereas in cases where the cause is external, like use of illegal drugs such as anabolic steroids, cutting the cause is the key to preventing gynaecomastia.

When should I see a doctor?

Gynaecomastia is not a medical emergency but this does not mean it should be put off. An appointment with your  GP regarding gynaecomastia should be made as soon as possible after any abnormal growth on either or both breasts are noticed. Although gynaecomastia itself is benign, there could be malignant underlying issues which may cause further health problems. 

Medical treatment to gynaecomastia is also ineffective after two years which means in order to avoid surgery, the condition should be checked and appropriately treated in a timely manner.4,6

How is gynecomastia diagnosed?

Diagnosis of gynaecomastia will be made by your doctor through physical examination and obtaining detailed medical history. The physical examination will include palpitation of breast tissue, evaluation of primary sexual characteristics (penile area) and secondary sexual characteristics (pubic and underarm hair, voice and muscle structure)  and searching for other lumps and signs around the body for other medical conditions such as prostate or testicular cancer.2


In summary, gynaecomastia is a relatively common occurrence of enlarged breast tissue in PAMAB. It can affect people of all ages although it is more common for it to occur in adolescents and PAMAB who are  over 50 years of age. Gynaecomastia itself is not a life threatening condition. Most of the reasons for gynaecomastia are benign and gynaecomastia itself is expected to resolve within two years. But there could be malignant underlying medical conditions which are causing gynaecomastia, that's why it needs to be checked by a medical professional to assist with the treatment.


  1. Wassersug RJ, Oliffe JL. The social context for psychological distress from iatrogenic gynecomastia with suggestions for its management. The Journal of Sexual Medicine [Internet]. 2009 Apr [cited 2023 Jul 26];6(4):989–1000. Available from: https://linkinghub.elsevier.com/retrieve/pii/S174360951532484X
  2. Narula HS, Carlson HE. Gynaecomastia—pathophysiology, diagnosis and treatment. Nat Rev Endocrinol [Internet]. 2014 Nov [cited 2023 Jul 26];10(11):684–98. Available from: https://www.nature.com/articles/nrendo.2014.139
  3. Johnson RE, Murad MH. Gynecomastia: pathophysiology, evaluation, and management. Mayo Clin Proc [Internet]. 2009 Nov [cited 2023 Jul 26];84(11):1010–5. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2770912/
  4. Niewoehner CB, Schorer AE. Gynaecomastia and breast cancer in men. BMJ [Internet]. 2008 Mar 29 [cited 2023 Jul 26];336(7646):709–13. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2276281/
  5. Deepinder F, Braunstein GD. Drug-induced gynecomastia: an evidence-based review. Expert Opinion on Drug Safety [Internet]. 2012 Sep [cited 2023 Jul 27];11(5):779–95. Available from: http://www.tandfonline.com/doi/full/10.1517/14740338.2012.712109
  6. Dickson G. Gynecomastia. afp [Internet]. 2012 Apr 1 [cited 2023 Jul 26];85(7):716–22. Available from: https://www.aafp.org/pubs/afp/issues/2012/0401/p716.html
  7. Cuhaci N, Polat SB, Evranos B, Ersoy R, Cakir B. Gynecomastia: Clinical evaluation and management. Indian J Endocrinol Metab [Internet]. 2014 [cited 2023 Jul 26];18(2):150–8. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987263/
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Kutal Mete Tekin

MRes, Bioengineering, Imperial College London

Kutal trained as a medical doctor in Istanbul before moving to London for this research masters at Imperial College London. He works as a part time medical interpreter with the NHS. His written work can also be seen in the motor sports sector as he has been a freelance sports writer and and editor since 2016.

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