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Condition

Gynaecomastia

Gynaecomastia explained: real causes, how it is diagnosed, and evidence-based treatment options — with sources, not guesswork.

Also known as: gynecomastia, enlarged male breast tissue

Symptoms6 listed
ICD-10N62
TreatableYes
DE
Medically reviewed by Dr. Elif Yılmaz, MD, FECSM
Last reviewed 22 July 2026
✓ Clinician reviewed
Gynaecomastia✓ Clinician-reviewed information
Key takeaways
  • Gynaecomastia is a benign growth of glandular breast tissue in men, caused by a shift in the balance between oestrogen and testosterone — it is distinct from pseudogynaecomastia, which is simply fat in the chest without true glandular growth.
  • It is extremely common and happens at three typical life stages: in newborns, during puberty, and in older age — the newborn and pubertal forms usually resolve on their own.
  • In adults, a proper work-up identifies an underlying cause — including certain medications, hormonal conditions, or, less commonly, liver or kidney disease — in roughly 45–50% of cases.
  • Male breast cancer is rare, and gynaecomastia itself is not considered a precancerous condition, though certain warning signs (a hard, fixed, asymmetric lump, nipple discharge, or skin changes) should always be assessed.
  • Treatment is not automatic or urgent in most cases — many cases are monitored, some resolve once an underlying cause is addressed, and surgery is one option among several rather than a default first step.

Overview

Gynaecomastia is real growth of breast gland tissue in men. It is not the same as simple chest fat, which is a separate thing called pseudogynaecomastia. The difference matters. True gynaecomastia feels like a firm, rubbery disc right under the nipple. Fat alone feels softer and more spread out. Many men have a mix of both. That is why a proper exam, not just a look in the mirror, is the place to start.

The cause, at its heart, is a shift in the balance of two hormones. Oestrogen makes breast tissue grow. Testosterone normally holds that growth in check. Anything that raises oestrogen, lowers testosterone, or blocks testosterone can tip the balance and trigger growth. That is why the list of possible causes is broad, from certain medicines to specific hormone and organ conditions.

It is very common, and happens at three stages of life. In newborn boys it is common and passes on its own in weeks to months. In puberty it is also common, from the normal hormone swings of that age, and most cases settle within one to two years with no treatment. This is worth saying clearly, because it can cause real distress at an age when body image already feels raw. Careful modern research even suggests that truly notable pubertal cases are less common than older, looser estimates claimed.

The third stage is older age, generally from the 60s on. Here several things add up: testosterone drifts down, body fat rises (and fat turns some testosterone into oestrogen), and older men are more likely to take a medicine that can cause it.

Adult gynaecomastia, outside those normal patterns, is where a proper check has the most value. A full work-up finds a specific, sometimes treatable cause in about 45 to 50% of adult cases. Medicines are one of the most common. So are low testosterone, an overactive thyroid, and liver disease, among others. Anabolic steroid use is a very relevant one. When no cause is found, that is a normal result too, not a sign something was missed. And one quiet worry deserves a plain answer: male breast cancer is rare, and gynaecomastia itself is not a pre-cancer. A few specific signs — a hard, fixed lump, nipple discharge, or skin changes — do need prompt, targeted checks.

Current clinical guidelines explicitly state that gynaecomastia itself should not be considered a precancerous or cancer-predisposing condition — male breast cancer is rare, accounting for a very small fraction of all male cancers.

Types of gynaecomastia

Neonatal
Common in newborn boys due to residual maternal oestrogen exposure; resolves spontaneously within weeks to months.
Pubertal
Occurs during adolescence due to normal, sometimes uneven pubertal hormone shifts; the large majority of cases resolve on their own within one to two years.
Adult / persistent
Occurs from the 20s through later life; more likely to reflect an identifiable underlying cause, particularly medication use or a hormonal condition, and warrants a proper work-up.
Senescent (older-age)
Common from the 60s onward, related to declining testosterone, increased body fat and aromatase activity, and cumulative medication use.
Pseudogynaecomastia (lipomastia)
Not true gynaecomastia; fat deposition in the chest without glandular tissue growth, common in men with excess body weight.
How common is it?
Reported prevalence varies enormously by age and diagnostic criteria, ranging from roughly 4% to 69% across studies, with 30–65% of adult men found to have some palpable breast tissue on careful examination. It follows a trimodal pattern — common in newborns, common during puberty (with rigorous recent population data suggesting a true clinically significant incidence closer to 1% among adolescent boys), and common again from the 60s onward, where prevalence is commonly reported at 36–57%.
Source: onlinelibrary.wiley.com

Symptoms

A firm, sometimes rubbery disc of tissue directly beneath and around the nipple, on one or both sides
Breast enlargement, ranging from subtle to significant
Tenderness or sensitivity, particularly in earlier or actively developing cases
Nipple sensitivity
Psychological distress, self-consciousness, or avoidance of certain activities such as swimming or removing a shirt
Warning features needing prompt evaluation: a hard, fixed lump; clearly one-sided enlargement; nipple discharge or bleeding; skin dimpling; or a lump not centred on the nipple

Causes

Physiological: newborn maternal oestrogen, normal pubertal hormone changes, and older-age hormonal shifts
Certain blood pressure medications
Some ulcer and acid reflux medications
Anti-androgen medications, including some used in prostate cancer treatment
Certain psychiatric medications
Anabolic-androgenic steroid use, both during use and sometimes after stopping
Hypogonadism (low testosterone) from a range of causes, including Klinefelter syndrome
Hyperthyroidism
Chronic liver disease, which reduces normal oestrogen clearance
Chronic kidney disease, or (uncommonly) hormone-producing tumours
Idiopathic — no specific cause identified despite a full work-up

Risk factors

Puberty and older age (the two physiological peaks)
Obesity, both directly and through coexisting pseudogynaecomastia
Use of medications recognised to cause gynaecomastia as a side effect
Anabolic steroid use
Chronic liver or kidney disease
Known hypogonadism or other hormonal conditions, including Klinefelter syndrome
Heavy alcohol use, partly via its effects on liver function and hormone metabolism

How it is diagnosed

Diagnosis starts with a detailed history — including medication use (prescription, over-the-counter, and recreational), duration and rate of enlargement, associated symptoms, and relevant background such as liver, kidney, or thyroid conditions — combined with a physical examination. On examination, a doctor assesses whether the enlargement is true glandular tissue (a firm, mobile disc under the nipple) or fat alone, and checks specifically for warning features.

Hormone testing is a standard part of an adult work-up, commonly including testosterone, oestradiol, LH, FSH, and thyroid function, with additional tests such as hCG or AFP if a hormone-producing tumour is suspected. Where the picture is unclear, or warning features are present, imaging — typically mammography or ultrasound of the breast tissue — is used to further characterise it and, where genuinely necessary, guide a biopsy to rule out malignancy. This is not a routine step for straightforward, typical-appearing gynaecomastia.

When to see a doctor
  • You notice new breast enlargement as an adult, outside the typical pubertal window
  • The enlargement is clearly asymmetric, hard, fixed, or associated with nipple discharge or skin changes
  • Pubertal gynaecomastia has not improved after one to two years, or is causing significant distress
  • You suspect a medication you are taking may be responsible
  • Gynaecomastia is accompanied by other symptoms, such as reduced libido, fatigue, or unexplained weight change
Reducing your risk
  • Reviewing current medications with a doctor if gynaecomastia develops after starting a new one, since a dose adjustment or alternative sometimes resolves it
  • Avoiding or reconsidering anabolic steroid use, given its well-documented association with gynaecomastia
  • Managing body weight, which can reduce the fat-related component even where it does not address true glandular tissue
  • Moderating alcohol intake, given its relevance to liver function and hormone metabolism
  • Managing underlying conditions such as thyroid disease, liver disease, or hypogonadism where identified

Common questions

How do I know if this is real gynaecomastia or just chest fat?
On examination, true gynaecomastia typically feels like a firm, rubbery, mobile disc directly beneath and centred around the nipple, whereas fat alone tends to feel softer and more evenly spread across the chest. Many men have a combination of both, which is exactly why a proper physical examination by a doctor, rather than self-assessment, is the reliable way to tell them apart.
Is gynaecomastia a sign of cancer?
Almost always, no — male breast cancer is rare, and gynaecomastia itself is not considered a precancerous condition by current guidelines. Certain specific features — a hard, fixed, asymmetric lump, nipple discharge, or skin changes — do warrant prompt evaluation, but the large majority of gynaecomastia, even when these features prompt investigation, turns out to be entirely benign.
Will my pubertal gynaecomastia go away on its own?
In the large majority of cases, yes — pubertal gynaecomastia typically resolves within one to two years as hormone levels stabilise, without needing treatment. If it has not meaningfully improved after this timeframe, or is causing significant distress in the meantime, it is reasonable to have it properly assessed rather than assuming it will keep resolving indefinitely.
Can exercise or diet get rid of gynaecomastia?
Diet and exercise can reduce the fat component of chest enlargement as part of general weight loss, but they cannot reduce true glandular breast tissue, which does not respond to exercise or "spot reduction" the way fat can. This is a common point of confusion — chest exercises build the muscle underneath but do not shrink glandular tissue sitting above it.
Can medications really cause gynaecomastia, and will it go away if I stop them?
Yes, medications are one of the most common identifiable causes of adult gynaecomastia, and in many cases stopping or changing the responsible medication leads to improvement over time. This is not a decision to make unilaterally with a medication prescribed for a genuine condition — it is a conversation to have with the prescribing doctor, weighing both issues together.
Does anabolic steroid use cause gynaecomastia?
Yes, this is a well-documented and common cause, occurring both during active use — as some steroids convert to oestrogen — and sometimes becoming more noticeable after stopping, as natural hormone production readjusts. Steroid-related gynaecomastia can be more resistant to simply stopping the substance than some other causes, and is a reasonable, non-judgemental thing to be upfront about with a doctor.
I am on testosterone replacement therapy — why would that cause gynaecomastia, not prevent it?
This can genuinely happen. A proportion of testosterone given as therapy is naturally converted into oestrogen in the body via the aromatase enzyme, and in some men this conversion is significant enough to trigger or worsen gynaecomastia, even while overall testosterone is being raised. This is worth discussing with the doctor managing your therapy, since dose or approach adjustments are sometimes possible.
Is gynaecomastia linked to Klinefelter syndrome?
Yes — gynaecomastia is a commonly described feature of Klinefelter syndrome, related to the low testosterone and altered hormone balance of the condition, though it is not present in every man with it. If you have both an unexplained hormonal picture and gynaecomastia, this is a reasonable thing to raise as part of a broader hormonal work-up.
Can liver or kidney disease cause gynaecomastia?
Yes, both are recognised causes. Chronic liver disease reduces the liver’s normal ability to clear oestrogen, allowing it to build up; chronic kidney disease can affect hormone balance through several mechanisms. This is part of why a thorough medical history, not just a breast examination, is a standard part of proper assessment.
Is one-sided (unilateral) gynaecomastia more concerning than two-sided?
It is not automatically more concerning, since unilateral gynaecomastia is a recognised and often entirely benign presentation, but it is generally taken as one factor — alongside hardness, fixation, or skin changes — that prompts more careful evaluation. Context matters more than symmetry in isolation.
What actually happens if no cause is found (idiopathic gynaecomastia)?
This is a common and entirely recognised outcome of proper investigation — not a sign that something was missed. Management then focuses on the gynaecomastia itself, through monitoring or treatment options if it is causing significant distress, rather than continuing to search indefinitely for an explanation that testing has not found.
Does gynaecomastia need to be surgically removed?
Not automatically — many cases are monitored, particularly pubertal cases likely to resolve, or managed by addressing an identified underlying cause. Surgery is a recognised and effective option for persistent, established, or significantly distressing cases, particularly once any underlying cause has been addressed, but it is one option among several rather than a mandatory first step.
Can marijuana or other recreational drug use cause gynaecomastia?
There is a recognised association between marijuana use and gynaecomastia in the clinical literature, alongside a smaller number of other substances, though the strength of this association is not as firmly established as for some prescription medications. It is a reasonable, non-judgemental thing to mention during a medical history, since it may be relevant to identifying a cause.
Does having gynaecomastia mean my testosterone is low?
Not necessarily — while low testosterone (or an altered testosterone-to-oestrogen ratio) is one recognised cause, many men with gynaecomastia have testosterone in a typical range, with the imbalance instead relating to relatively elevated oestrogen, medication effects, or other factors. This is exactly why hormone testing, rather than assumption, is part of a proper work-up.
Will insurance or healthcare systems typically cover gynaecomastia surgery?
This varies considerably by country, healthcare system, and individual circumstances, including whether it is classified as medically necessary versus cosmetic in your situation — a practical question best answered directly by your insurer or healthcare provider rather than assumed from general information.

Sources

  1. Management of gynecomastia: SIAMS clinical practice guidelines. J Endocrinol Invest. 2025/2026. https://link.springer.com/article/10.1007/s40618-026-02915-2
  2. Kanakis GA, et al. EAA clinical practice guidelines — gynecomastia evaluation and management. Andrology. 2019;7(6). https://onlinelibrary.wiley.com/doi/10.1111/andr.12636
  3. Berger O, et al. Pubertal gynecomastia incidence among 530,000 boys. Front Pediatr. 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10953823/
  4. Endotext (NCBI Bookshelf). Gynecomastia: Etiology, Diagnosis, and Treatment. https://www.ncbi.nlm.nih.gov/books/NBK279105/
  5. NHS. Gynaecomastia. https://www.nhs.uk/conditions/gynaecomastia/