Examining the Causes of Gynecomastia

By Dr. Ashley Cowan, pediatric resident at CHOC

Gynecomastia is breast tissue that forms in males.  Males can also have excess adipose (fat cells) tissues in this same region, but gynecomastia is different. Typically, the formation of this breast tissue is caused by an imbalance of estrogen and androgens in the body, which is very common in the early stages of puberty. While it may or may not be noticeable to others, this tissue often will feel like a firm bump, and is sometimes tender. Commonly it occurs on both sides of the chest, but it may also appear on only one side.

This condition is surprisingly common. Up to two-thirds of boys actually develop gynecomastia during puberty, and it’s considered a normal part of adolescent development. For the majority of males it is temporary, usually lasting anywhere from six-12 months. There are three times in a male’s life when breast tissue may form:

  • As a newborn- 60-90 percent of male babies have gynecomastia from exposure to the mother’s estrogen.
  • During puberty- it might develop during early puberty, but usually resolves on its own.
  • Later in life- elderly men often develop breast tissue as the result of a decrease in testosterone levels.

There are some medications that can cause gynecomastia including gabapentin, an anti-epileptic medication; metoclopramide, prescribed for stomach and esophageal problems; ulcer and acid reflux medications like ranitidine or omeprazole, and some antipsychotic medications such as risperidone. In fact, over 300 medications have potentially been associated with the development of breast tissue, usually reversible when the medication is discontinued. Herbal or ‘natural’ medications that contain estrogen also can lead to gynecomastia. Steroids, alcohol, heroin and heavy marijuana use also can stimulate the development of breast tissue.

There are a few rare syndromes and other causes for breast tissue development, which is why it is important to discuss the presence of breast tissue with your primary care provider.  These causes can include:

  • Hyperthyroidism or renal and liver disease. These can affect the balance of hormones in the body.
  • Certain tumors that produce estrogen.
  • Some genetic syndromes that may also lead to altered estrogen and testosterone levels.

If your child has breast tissue development between the ages of 3 months and before puberty has started, if the breast tissue that developed is larger than 4 cm, or if it occurs after puberty has completed, consult your child’s pediatrician. Be sure to let your doctor know if you notice discharge or liquid coming from the nipples or if the breast tissue is not resolving.  Your provider will help determine if any additional testing is needed.

The majority of patients have physiologic (normal) and temporary causes of gynecomastia. Typically, this breast tissue will resolve on its own and no intervention is needed. It can take from a few months up to two years to resolve completely. The breast tissue itself is not harmful and surgery should only be considered for those with significant distress for cosmetic reasons.

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2 thoughts on “Examining the Causes of Gynecomastia”

    1. For people who experience gynecomastia, the changes can be permanent or temporary. It’s not easy to predict when it will be permanent vs temporary. Most trans youth who want breast tissue to develop will need to use hormones that cause breast development. There is no special diet, exercise program, and so on that would make the gynecomastia stay or that would cause breast development.
      It can be very hard to talk to your parents or even your doctor about your gender, but it’s important to start the conversation with them if you feel safe doing so. You can also ask for a referral to a specialist who has experience in helping trans youth – like an adolescent medicine specialist, an endocrinologist, etc. If you are not able to ask your parent or doctor for a referral, it might be helpful to get support from programs like OC Accept ( or the LGBT Center OC (

      Options for referral for transgender care for youth in OC:
      CHOC adolescent medicine
      CHOC Endocrinology GPS program
      UCI gender diversity program:

      Some youth become very distressed about not being able to talk to any adults about their gender or transition needs. If you’re experiencing difficulty and/or are feeling unsafe, reach out to someone for help:
      A teacher, school counselor, trusted adult.
      At the trans lifeline ( 877-565-8860
      At the Trevor project ( call 1-866-488-7386 or Text “START” to 678678 or Chat with them online.

      -Dr. Terez Yonan, adolescent medicine specialist at CHOC Children’s

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