Hormones and Breast Discharge

Hormones play a major role in breast health, and changes in hormone levels can sometimes lead to nipple or breast discharge. Shifts in estrogen, progesterone, and prolactin commonly cause breast discharge. These hormones affect breast tissue, milk ducts, and fluid production, which explains why discharge often appears during pregnancy, breastfeeding, or around menstrual cycles.

Breast discharge does not always signal disease. It can result from natural body changes, certain medications, or stimulation of the breast. Sometimes, it can signal conditions like duct problems, infections, or—less often—breast cancer. Recognizing the difference between normal and abnormal causes helps people know when to seek medical advice.

Definition of Symptom

Nipple discharge means fluid comes out of one or both nipples. The fluid can have different colors and textures, and it may happen with or without touching the breast. Some types are linked to hormones, while others may point to another condition.

Types of Breast Discharge

Milky Discharge: Often linked to hormonal changes, pregnancy, or breastfeeding.
Bloody Discharge: May signal a more serious cause such as a growth in the breast ducts.
Clear Discharge: Can result from hormonal shifts or benign conditions.
Green Discharge: Sometimes connected to infections or blocked ducts.

The symptom varies in appearance and is not always abnormal. For example, a milky fluid may appear when hormone levels rise, even outside of pregnancy. In contrast, a bloody or pus-like discharge is more concerning and should be checked by a doctor.

Discharge may come from one breast or both. It can be spontaneous or only occur when the nipple is pressed. The context of the symptom, including color, consistency, and whether it is single-sided, helps guide further evaluation.

In many cases, hormone-related changes explain the symptom. Estrogen, progesterone, and prolactin play key roles in causing or regulating nipple fluid. However, when discharge is persistent, unusual in color, or comes with other breast changes, it may suggest a condition that needs medical review.

Possible Causes/Diseases Condition

Several conditions can cause breast discharge, including hormone changes, infections, or growths. The cause often depends on the type of fluid, whether it affects one or both breasts, and if other symptoms are present.

Hormonal causes include galactorrhea, which happens when high prolactin levels trigger milk-like discharge outside of pregnancy or breastfeeding. Hypothyroidism may also play a role, since low thyroid hormone can increase prolactin.
Benign breast conditions can also cause discharge. Fibrocystic breast changes may lead to discharge and breast tenderness. An intraductal papilloma, a small growth inside the milk duct, can cause clear or bloody discharge. Duct ectasia, or widening of ducts, may lead to thick, sticky fluid.
Infections and inflammation such as mastitis or a breast abscess can produce pus-like or bloody discharge. These conditions often bring pain, redness, or swelling. Breast infections are more common during breastfeeding but can happen at other times as well.
Tumors and cancer can sometimes cause discharge. A benign tumor may cause discharge without other serious symptoms. Breast cancer can present with bloody or persistent fluid from one nipple, especially if it is not linked to pregnancy or breastfeeding.

Condition	Possible Discharge Type	Other Clues
Galactorrhea	Milky	Not pregnant or nursing
Intraductal papilloma	Clear or bloody	Single duct, one breast
Mastitis/Abscess	Pus-like or bloody	Pain, swelling, fever
Duct ectasia	Thick, sticky, green/brown	Older age, duct widening
Breast cancer	Bloody or watery	Lump, skin changes

Other Non-Disease Causes

Not all nipple discharge comes from illness. Certain everyday factors can cause fluid release without signaling a medical problem. These often relate to body changes, habits, or common medications.

Nipple stimulation often causes non-disease discharge. This can happen during sexual activity, self-exams, or even friction from clothing. The stimulation may prompt a small amount of clear or milky fluid.
Medications can also play a role. Some drugs affect hormone levels, which can lead to discharge. Examples include:

Medication Type	Possible Effect on Discharge
Birth control pills	Hormonal shifts may cause milky fluid
Antidepressants	Can affect prolactin levels, leading to leakage
Other hormone-related drugs	May disrupt normal breast secretions

Herbal supplements are another factor. Products such as fenugreek or fennel, often used to support lactation, may increase the chance of discharge even in women who are not breastfeeding.

These causes are often temporary. When the trigger is removed—such as stopping a supplement or changing a prescription—the discharge may lessen or stop. While these situations are not linked to disease, it is helpful to note the pattern, color, and frequency of the fluid. This helps a person and their healthcare provider decide if further checks are needed.

How It Causes the Symptom

Hormones control how breast tissue develops and works. When these hormone levels shift, the breast ducts and glands may release fluid from the nipple. Prolactin, made by the pituitary gland, plays the main role. High prolactin levels can cause milk-like discharge, even when a person is not pregnant or breastfeeding.

Other hormones, such as estrogen and progesterone, also affect breast tissue. Changes in these hormones around the menstrual cycle can cause temporary discharge. A hormonal imbalance may lead to discharge that is unexpected or lasts longer than normal. This imbalance can come from natural changes, certain medicines, or conditions that affect the pituitary gland.

Common Hormone-Related Causes

Pregnancy and breastfeeding – natural rise in prolactin and estrogen.
Menstrual cycle shifts – short-term changes in estrogen and progesterone.
Pituitary disorders – excess prolactin production.
Medication effects – some drugs raise prolactin levels.

Hormone	Effect on Breast	Possible Symptom
Prolactin	Stimulates milk production	Milky discharge
Estrogen	Changes breast ducts	Clear or whitish discharge
Hormonal imbalance	Disrupts normal patterns	Ongoing or unexpected discharge

Discharge linked to hormones often affects both breasts and is usually not a sign of cancer. However, discharge that is bloody or only from one breast may suggest another, non-hormonal cause.

Possible Complications

Breast discharge linked to hormones is often harmless, but complications can develop if the discharge signals an underlying problem. Some causes may need attention to prevent further health issues. Potential complications include:

Infection: Bacteria in breast tissue can cause pain, swelling, and pus-like discharge.
Breast abscess: Untreated infections may cause a pocket of pus that needs drainage.
Tumors: Both benign growths and, less commonly, breast cancer can cause abnormal discharge.

Discharge that is bloody, clear, or comes from only one nipple may raise concern. These cases can point to growths in the milk ducts or other changes in the breast. Certain medications or hormone treatments can also complicate things by altering hormone levels. This can make it harder to tell whether the discharge is normal or linked to a problem.

Type of Complication	Possible Sign	Why It Matters
Infection	Redness, fever, pus	Can spread if untreated
Duct growths	Bloody or clear fluid	May signal benign or malignant changes
Hormonal imbalance	Milky discharge outside pregnancy	May indicate thyroid or pituitary issues

When to Seek Medical Attention

Nipple discharge often happens because of hormonal changes, but not all discharge is harmless. See a healthcare professional if fluid appears without squeezing, especially if it is bloody, clear, or occurs in only one breast. Warning signs that need prompt care include:

Discharge that is red, brown, or bloody
Fluid that comes out on its own, without pressure
Discharge from only one nipple
A lump, swelling, or pain in the breast

Doctors may use imaging tests to check for underlying causes. A mammogram can find changes in breast tissue, and an ultrasound can help find cysts or masses that might not appear on an X-ray.

If imaging shows an abnormal area, doctors may take a sample of tissue for closer examination. This step helps find or rule out conditions like infection, duct problems, or, in rare cases, breast cancer.