Causes

Galactorrhea often results from having too much prolactin — the hormone responsible for milk production when you have a baby. Prolactin is produced by your pituitary gland, a small bean-shaped gland at the base of your brain that secretes and regulates several hormones.

Possible causes of galactorrhea include:

• Medications, such as certain sedatives, antidepressants, antipsychotics and high blood pressure drugs
• Opioid use
• Herbal supplements, such as fennel, anise or fenugreek seed
• Birth control pills
• A noncancerous pituitary tumor (prolactinoma) or other disorder of the pituitary gland
• Underactive thyroid (hypothyroidism)
• Chronic kidney disease
• Excessive breast stimulation, which may be associated with sexual activity, frequent breast self-exams with nipple manipulation or prolonged clothing friction
• Nerve damage to the chest wall from chest surgery, burns or other chest injuries
• Spinal cord surgery, injury or tumors
• Stress

Idiopathic galactorrhea

Sometimes doctors can't find a cause for galactorrhea. This is called idiopathic galactorrhea, and it may just mean that your breast tissue is particularly sensitive to the milk-producing hormone prolactin in your blood. If you have increased sensitivity to prolactin, even normal prolactin levels can lead to galactorrhea.

Galactorrhea in men

In males, galactorrhea may be associated with testosterone deficiency (male hypogonadism) and usually occurs with breast enlargement or tenderness (gynecomastia). Erectile dysfunction and a lack of sexual desire also are associated with testosterone deficiency.

Galactorrhea in newborns

Galactorrhea sometimes occurs in newborns. High maternal estrogen levels cross the placenta into the baby's blood. This can cause enlargement of the baby's breast tissue, which may be associated with a milky nipple discharge. This milky discharge is temporary and resolves on its own. If the discharge is persistent, the newborn should be evaluated by a doctor.