What are the causes of breast enlargement (gynecomastia)?

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Last updated: April 13, 2025View editorial policy

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From the Research

Breast enlargement can occur due to various causes including hormonal changes, weight gain, medications, medical conditions, and normal development, with hormonal changes being a primary factor, as seen in studies such as 1 that discuss the effects of tamoxifen on breast cancer patients. The causes of breast enlargement can be broken down into several categories, including:

  • Hormonal changes: During puberty, hormones trigger breast tissue growth in females, and fluctuations in hormone levels during pregnancy, breastfeeding, and menopause can also affect breast size, as discussed in 2.
  • Weight gain: Increases fat deposits in breasts, leading to enlargement, which is a common side effect of certain medications, such as tamoxifen, as mentioned in 3.
  • Medications: Certain medications like hormonal contraceptives, hormone replacement therapy, antipsychotics (risperidone, haloperidol), and some antidepressants can cause breast enlargement, as noted in 4.
  • Medical conditions: Conditions such as gynecomastia in men (from hormonal imbalances, liver disease, or certain medications), breast cysts, fibroadenomas, and inflammatory conditions can also lead to enlargement, as discussed in 5.
  • Normal development: Breast growth during puberty and changes in breast size during pregnancy and breastfeeding are normal developments that can lead to breast enlargement. It is essential to note that while these factors can contribute to breast enlargement, if the enlargement occurs suddenly, is painful, or is accompanied by concerning symptoms, medical evaluation is recommended to determine the underlying cause and appropriate treatment, as suggested by the studies 2, 3, 1, 5, 4.

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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