• Milky nipple discharge not associated with lactation, defined as >1 year after pregnancy or cessation of breastfeeding
  • Does not include serous, purulent, or bloody nipple discharge
  • System(s) affected: endocrine/metabolic, nervous, reproductive

Pediatric Considerations
Can occur in infants secondary to maternal estrogen exposure

Pregnancy Considerations

  • Pregnancy stimulates lactotroph cells, so pituitary prolactin-secreting macroadenomas may increase by 21% (1)[A].
  • Milk production often begins during the 2nd trimester; milk leakage that occurs during pregnancy is not pathophysiologic galactorrhea.


Predominant age: 15 to 50 years (reproductive age), most commonly ages 20–35; third most common breast complaint in women

Marked variability reported

Approximately 20–25% of women experience galactorrhea in their lifetime.

Etiology and Pathophysiology

  • Oxytocin stimulates prolactin secretion, which induces lactation. Prolactin is secreted by the anterior pituitary and inhibited by dopamine produced in the hypothalamus.
  • Galactorrhea results either from prolactin overproduction or from loss of inhibitory regulation by dopamine.
  • Physiologic galactorrhea is due to pregnancy or from nipple stimulation, piercing.
  • Pathophysiologic galactorrhea
    • Hyperprolactinemia (craniopharyngiomas, other tumors; irradiation; traumatic brain injury; pituitary stalk compression; postbreast augmentation surgery [1%]; prolactinoma [sellar tumor, somatotroph adenoma, pituitary macroadenoma]; vascular malformations [aneurysms])
    • Hyperprolactinemia in systemic diseases (adrenal insufficiency, chronic kidney disease, cirrhosis, thyroid disease, lung cancer, renal cell cancer, sarcoidosis/histiocytosis)
    • Nonhyperprolactinemia
      • Chest wall trauma; spinal cord injury
      • Chiari-Frommel, del Castillo, and Forbes-Albright syndromes
      • Herpes zoster
  • Medications/substances:
    • Cardiovascular (α-methyldopa, reserpine, verapamil, spironolactone)
    • GI (domperidone, H2 blockers, metoclopramide, proton pump inhibitors) (2)[C]
    • Herbal (anise [licorice], barley, blessed thistle, fenugreek seed, fennel, goat’s rue)
    • Illicit (cocaine, marijuana)
    • Anti-infectives (isoniazid, protease inhibitors)
    • Opioids
    • Psych/neuro (neuroleptics, antipsychotics, stimulants, SSRIs, SNRIs [prolactin not always elevated], tricyclic antidepressants, MAOIs) (3)[C]
    • Reproductive (estrogens, copper IUD)
    • DMARDs (azathioprine)
  • Normal prolactin levels (if patient has galactorrhea plus amenorrhea, likely can have microprolactinoma)

Risk Factors

See “Etiology and Pathophysiology.”

General Prevention

  • Avoid frequent nipple stimulation.
  • Avoid medications that can suppress dopamine.

Commonly Associated Conditions

See “Etiology and Pathophysiology.”

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