Mammary gland secretion

Mammary gland secretion (or galactorrhea) is the leakage of fluid from the nipple.

In a man, mammary gland secretion means in any case a pathological event and should be examined.

In a woman who is not pregnant or breastfeeding, these secretions are not necessarily abnormal, but this should be decided by a doctor.

Most disorders that cause mammary gland secretion:

  • Are not serious,
  • Can be easily treated.

Usually, regardless of the cause of the discharge, the person has no other symptoms.

In some cases, discharge may be one of the first symptoms of a tumor:

  • At the chest,
  • On the pituitary gland.

To establish the cause of secretion, the doctor must analyze:

  • Color
  • Origin
  • Causative activity.


Causes of mammary gland secretion unrelated to pregnancy

Ductal papilloma

The ductal papilloma can be the cause of outflow of blood, which occurs only on one breast.

The papilloma is a tissue mass (benign tumor) similar to a condyloma (cauliflower-like thickening of the skin), usually has a size of 1-2 cm and is localized inside one of the milk ducts.

These ducts transport the milk from the gland to the nipple.

As a rule, the papilloma develops behind the nipple and can cause the discharge of:

  • Liquid
  • Blood.

Usually, only a single papilloma occurs, which can be easily removed.

Even though this discharge can be unsettling, it is important to know that this mass of tissue does not carry the risk of turning into a breast tumor.

However, it should be checked by a doctor to rule out breast cancer and initiate therapy.

Dilation of the gland ducts

If the discharge is brown, green or yellowish, it may be a harmless disease called mammary ductectasia.

Mammary gland ductectasia consists of the dilation of a milk duct in the lower breast area and most commonly affects women near menopause.

As the breasts age, the milk ducts behind the nipple become:

  • Shorter
  • Wider.

The result is a congestion of breast secretions, which can cause secretion leakage.

This is an age-related physiological change and should not be worrying.


  • If you feel a lump behind the nipple, which consists of scar tissue,
  • The nipple may be retracted.

Even if this change is harmless and passes without treatment, it is important to talk about it with the doctor to rule out a breast neoplasm.

If the disease progresses, a tissue mass (also plasma cell mastitis) can develop from it, which imitates cancer.

An operation is performed only if:

  • a tumor mass forms,
  • The secretion contains blood and may be mixed with serum.

Widening of the gland ducts does not pose an increased risk for the future development of breast cancer.

Breast abscess

An abscess on the breast or around the nipple can lead to pus-containing secretion discharge.

An abscess is an accumulation of pus that forms under the skin after a bacterial infection.

The surrounding skin can be:

  • Reddened
  • Hot
  • Turgid.

A breast abscess can be the complication of mastitis (inflammation of the nipple).

If a woman has mastitis, the doctor may prescribe antibiotics.

If the breast continues to be hard, reddened and painful after taking the antibiotics, the doctor may refer it to a specialist centre to confirm the diagnosis of a breast abscess.

Breast cancer

Bloody secretion from the nipple is the initial symptom in 5 – 12% of women with breast cancer (A prospective study of nipple discharge. Carpenter R, Adamson A, Royle GTBr J Clin Pract Suppl. 1989 Nov; 68():54-7; discussion 67-72).

Other signs to study that increase the possibility of breast cancer include:

  • lumps on the breast or changes in breast shape,
  • secretions that come only from a nipple,
  • Discharge occurs without any pressure on the breast or nipple,
  • Age over 50 years.

In these cases, the doctor advises a mammogram, i.e. an X-ray examination that shows the condition of the breast and existing calcifications or tumor masses.

Trauma and pressure on the chest

Sometimes trauma to the chest (for example, a bruise caused by the steering wheel in a car accident) can injure the milk ducts and cause secretion from the nipple.

Another common cause is continued and repeated manipulation of the breast (self-palpation or palpation by the partner to look for lumps in the breast), which can lead to discharge from the nipple.


Some studies show that high psychological or physiological stress levels can increase the production of the hormone prolactin.

This hormone stimulates milk production. Usually this happens in pregnant women and lasts during the lactation period.


Side effects often appear.

There are medications that can increase prolactin levels and thus cause secretion from the nipples.

Some drugs that can provoke secretions from the mammary gland are:

  • antipsychotics such as Risperdal,
  • antiemetics such as metoclopramide,
  • Antihypertensives such as verapamil or methyldopa.
  • Opiates such as codeine (for example, found in some cough syrups) or morphine.
  • Tranquilizers and antidepressants such as selective serotonin reuptake inhibitors (SSRIs).

Less common causes of nipple secretion

Rare causes may include:

  • Contraceptives: As a rule, mammary gland secretion is only a temporary side effect when you start taking the pill (some women have a painful and swollen breast). The discharge is dark and occurs on both breasts.
  • Changes in hormone levels associated with puberty and menopause. When estrogen levels are elevated, these hormones can stimulate breast tissue. Secretions occur on both sides and are brownish.
  • Past lactation: Some women continue to produce breast milk for up to two years after breastfeeding.
  • Stimulation of the nipples, for example during sexual intercourse.
  • Prolactinoma, a benign tumor on the pituitary gland that increases prolactin levels.
  • Hormonal dysfunction such as hypothyroidism or Cushing’s disease.
  • Clogged milk duct, also called galactorocele, which occurs after childbirth when the woman does not breastfeed immediately and milk congestion occurs.

Secretion from the breast at the onset of pregnancy

In the first weeks of pregnancy, the increase in female hormones causes greater blood flow to the breast.

The result is that the breast swells and hurts.

In addition to these symptoms, there may be a clear secretion.

Thus, the body begins to keep the channels free for:

  • colostrum (a serous, yellow fluid secreted by women in the first few days after giving birth),
  • Milk.

The period in which the secretions occur can vary from woman to woman.

Dr. Miriam Stoppard writes in her book “Conception, Pregnancy and Childbirth” that at the beginning of a pregnancy, a small amount of clear fluid can leak from the breast. For most women, however, this does not occur until the second trimester of pregnancy.

Some women do not have a discharge of secretions until the end of their pregnancy.

There is no need to worry about this, because this is normal and does not mean that the woman has too little milk.

Color of the escaping secretion

  • Bloody secretion discharge from red to dark brown: This is the type of secretion discharge that should worry the most, because it can be a sign of cancer. This may be caused by cancer that occurs in only one breast and not both.
  • A secretion that is bloody does not necessarily mean that it is cancer; it can also be the result of trauma to the breast or a benign papilloma.
  • In this case, the following examinations may be carried out:
    • Mammography
    • echography to search for enlarged lymph nodes,
    • Biopsy of a sentinel lymph node.
  • Viscous/sticky, greenish or black secretions: This is usually the result of breast canal ectasia, a common condition in women between 40-50 years of age. Ectasia is the dilation of one or more milk ducts, very similar to an internal pustule.
  • Rarely, this can cause chest pain. The doctor must check and determine whether the extension is so large that antibiotics must be taken.
  • White, clear and milky secretion: it often occurs as a hormonal disorder.
  • The doctor needs to do a thorough examination, because galactorrhea could indicate a disease elsewhere in the body, for example, hypothyroidism or pituitary dysfunction.
  • Greenish or brown secretion: This could indicate fibrocystic mastopathy (cysts in the breast). About half of women develop this unpleasant condition during their lifetime. It is mainly characterized by lump formation and chest pain, often the affected women undergo a biopsy. In most cases, it is a benign disease.
  • Secretion of pus (yellowish): It can be the result of an abscess caused by bacteria that can penetrate the breast through a wound (rhagade) in the nipple. Pus may leak from the chest and it may be swollen and inflamed.
  • Anyone who suspects suffering from an abscess should consult a doctor.
  • Multicolored and sticky secretion: Milk duct dilation or comedonestitis can produce a multicolored and sticky secretion and often occurs on both sides in premenopausal women.
  • This extension of the end sections of the milk ducts leads to:
    • accumulation of a lipid-containing, irritating fluid,
    • development of an inflammatory reaction,
    • secretion from the nipple,
Color of breast secretionPossible cause
Yellowish, white or dark greenNormal (physiological)
Clear, straw yellowOnset of pregnancy
or a pituitary tumor
Thin, milkyPregnancy or breastfeeding
Bloody spottedIntraductal papilloma,
breast cancer
PusChest infection
Milky or clear,
possibly yellow or green
Yellow, green, brown or blackDuctectasia,
fibrocystic breast disease

Mammary gland secretion: when to fear?

Secretions from the nipples can be an early symptom of breast cancer, but in most cases the cause is benign.

Guidelines for differential diagnosis:

1) Spontaneous secretion: Secretions that occur without pressure on the chest are the only ones that can have a tumoral origin.

Do secretions occur only when pressed:

  • Are they not worrying,
  • If you refrain from pressing on the nipple,
  • You should check the bra in the morning to see if there has been discharge at night (if the chest is not touched).

2) Color: In a serious illness, the secretions are clear (watery) or bloody in color.

If the color is greenish or milky, the secretion is usually benign.

If the secretions are abundant and milky, although not breastfed, one should consult the doctor to rule out a pituitary tumor (the pituitary gland).

3) From how many channels secretions occur: If a woman squeezes her breast and notices a secretion from several parts of the nipple, this generally does not have to be a concern.

However, if the secretions always occur from the same nipple area, you should consult the doctor.

4) Secretion from a single nipple: If the secretions occur only on one nipple, the cause may be malignant.

Secretion from the breast in the lactation period

Lactation and postpartum period: Women who have just given birth produce breast milk even when they are not breastfeeding.

This is one of the most common causes of benign secretion from the breast.

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