Galactorrhea (Milky Nipple Discharge)

What galactorrhea looks like

Galactorrhea is typically:

• milky white, sometimes slightly yellow or green
• from both breasts and from several ducts in each nipple
• spontaneous or only when the nipple is squeezed

Discharge that is bloody, clear and watery, from one duct, or from one breast is not galactorrhea. It needs a breast assessment, because it can come from a duct papilloma or, rarely, breast cancer. See nipple discharge for those patterns.

Why it happens: prolactin

Prolactin is made by the pituitary gland at the base of the brain. It stimulates the breasts to make milk. Its release is held in check by dopamine from the hypothalamus. Anything that raises prolactin, blocks dopamine, or stimulates the breast can trigger milk production. High prolactin also suppresses reproductive hormones, which is why galactorrhea often comes with period changes, low libido and infertility. This state is called hyperprolactinemia.

Causes of galactorrhea

Medicines (very common)

• Antipsychotics: risperidone, haloperidol, and many others
• Anti-nausea and reflux drugs: metoclopramide, domperidone
• Antidepressants: SSRIs and tricyclics, occasionally
• Blood pressure drugs: verapamil, methyldopa
• Opioids and estrogen-containing pills
• Recreational drugs: cannabis, opiates

Pituitary and brain causes

• Prolactinoma: a benign tumor that makes prolactin. The most common hormone-producing pituitary tumor. Small ones (under 1 cm) are most common in women.
• Other pituitary or hypothalamic tumors that press on the pituitary stalk and block dopamine, raising prolactin modestly.
• Head injury, radiation, or inflammatory disease of the pituitary.

Other medical conditions

• Hypothyroidism: low thyroid hormone raises TRH, which stimulates prolactin.
• Chronic kidney disease and cirrhosis: reduce prolactin clearance.
• Chest wall irritation: shingles, surgery, burns, tight clothing, or nipple piercing.
• Frequent breast stimulation: repeated self-examination or sexual stimulation.
• Polycystic ovary syndrome, stress and intense exercise can cause mild rises.

No cause found

When prolactin and imaging are normal, it is called idiopathic galactorrhea. It is often linked to recent pregnancy or breast sensitivity to normal prolactin levels and is usually harmless.

Galactorrhea in men and newborns

In men, galactorrhea is uncommon and nearly always reflects high prolactin. It often comes with erectile dysfunction, low sex drive and breast enlargement, and a prolactinoma in men is more often large at diagnosis. Newborns can briefly produce "witch's milk" from maternal hormones; it settles on its own within weeks and the nipples should not be squeezed.

Symptoms that may come with it

How it is diagnosed

1. History: all medicines and supplements, pregnancy and breastfeeding history, periods, headache and vision, chest wall injuries.
2. Breast exam to confirm a milky, multi-duct discharge and check for lumps.
3. Pregnancy test.
4. Blood tests: prolactin (ideally taken in the morning, not right after a breast exam or exercise), TSH, kidney and liver function.
5. Pituitary MRI if prolactin is raised and medicines or hypothyroidism do not explain it.
6. Visual field test if a large pituitary tumor is found.
7. Mammogram or ultrasound only if the discharge is not milky, or a lump is felt.

Treatment

• No treatment: if prolactin is normal, periods are regular and the discharge is mild, reassurance is enough. Avoid squeezing the nipples, which keeps milk production going.
• Change the medicine: if a drug is responsible, the prescriber may switch it. Do not stop antipsychotics or other important medicines without talking to the prescriber.
• Treat the cause: thyroid hormone replacement for hypothyroidism usually stops the discharge.
• Dopamine agonists: cabergoline or bromocriptine lower prolactin, shrink most prolactinomas and restore periods and fertility.
• Surgery or radiation: for prolactinomas that do not respond or cannot be tolerated, usually by surgery through the nose.

Discharge usually decreases within weeks to months once prolactin falls.

Frequently asked questions

Is galactorrhea a sign of cancer?

Galactorrhea, meaning milky discharge from both breasts, is very rarely a sign of breast cancer. It usually reflects high prolactin. Prolactinomas are benign. Bloody, watery or one-sided discharge, or a breast lump, is different and needs a breast assessment.

Can stress cause galactorrhea?

Physical and emotional stress can raise prolactin modestly, which may contribute to mild galactorrhea. Stress alone is rarely the whole explanation, so doctors still check prolactin, thyroid function and medicines before putting it down to stress.

Can men have galactorrhea?

Yes, although it is uncommon. In men, milky discharge almost always means high prolactin, often from a prolactinoma or medicines. It often comes with low sex drive, erectile problems or breast enlargement and should always be checked with blood tests.

Is it normal to have milky discharge years after breastfeeding?

A small amount of milky fluid on squeezing can persist for a year or two after weaning, especially with frequent checking. If it is spontaneous, persists longer, or comes with missed periods or headaches, see a doctor for a prolactin test.

Will galactorrhea go away on its own?

It often settles if the trigger stops, such as frequent nipple stimulation or a medicine that is changed. Discharge caused by a prolactinoma or hypothyroidism needs treatment of that cause. Idiopathic galactorrhea may persist but is harmless.