It is possible to have your breasts express some liquid during your reproductive years. Sometimes, it's even normal, like when you're pregnant or when you've had a baby and you're breastfeeding. But there are other times that your nipples may discharge fluid, and it is abnormal, or the result of an underlying condition. In essence, we're saying that there are causes of nipple discharge that you should know and watch out for.
To this effect, we have outlined some of these causes of nipple discharge below. Have a look!
See These Causes Of Nipple Discharge You Should Watch Out For

Women have several reasons why their nipples may secrete fluid. One of the most common causes of nipple discharge in women is the fluid that leaks from a woman's breasts when she stops breastfeeding. sometimes, it can go on for as long as 2 or 3 years after breastfeeding has stopped.
Pregnancy-Induced Discharge
Discharges from the breasts are quite normal in pregnancy. First, when colostrum comes in, and then after the baby is born. Colostrum, the first secretion from the mammary glands after giving birth, usually appears thin and light-yellow in color and turns thicker and milky white later on.
Inflamed or Irritated Nipples
Your nipple ducts can become inflamed or irritated from excess stimulation during sex. According to research, rough clothing or even a tight bra could also cause inflammation. And all of this can cause your nipples to discharge fluid.
Fibrocystic Changes
Women who have fibrocystic breasts in their reproductive ages may have nipple discharge right before their period. Fibrocystic breasts are lumpy and sometimes painful. The discharge from a fibrocystic breast could be yellow-green or brown in colour.
Infections
There's a breast infection known as mastitis. It causes the nipple to discharge pus-like yellow-green fluid along with a fever, pain, and breast tenderness. Also, breast or nipple abscesses cause nipple discharge. The discharge is similar to mastitis and smells bad too. A breast abscess is a localized area in which the body has "walled off" an infection.
See These Additional Causes Of Nipple Discharge

Blocked Milk Ducts
Blocked milk ducts are also called mammary duct ectasia; it is is a condition you'll most often find in women nearing menopause or after menopause. When your breast ducts widen and become clogged with thick discharge, doctors will diagnose blocked milk ducts. The discharge can be green, brown, or even black, and very thick and cheese-like. Nipple tenderness and redness are some other symptoms of this condition. Mammary duct ectasia usually goes away in time, but sometimes treatment will involve surgery.
Galactorrhea/Hyperprolactinemia
Sometimes, women who are not breastfeeding get a milky discharge, as if they were breastfeeding. It could also happen to men or even young children. It is called Galactorrhea, and most often it is the result of increased levels of prolactin in the blood. Prolactin is a hormone secreted by the pituitary gland that's involved with breast development and breastfeeding.
Intraductal Papillomas
These are usually benign growths that, by and large, involve only a single duct. They are most common in pre-menopausal women and often cause a clear or bloody discharge. You may feel a lump on the nipple, but it's often not tender.
Breast Cancer
For 7-15% of people with nipple discharge, breast cancer is responsible. Breast cancer is not a popular cause of nipple discharge; but it is often an early warning sign of breast cancer that is still in the pre-invasive stage. Mostly, when it happens to someone over the age of 40, the following apply:
- Discharge is one-sided and occurs spontaneously
- Discharge is bloody
- Other symptoms of breast cancer, such as skin changes (dimpling or retraction), nipple inversion, a breast mass, etc., are present
- Discharge occurs from only one duct of the tree-branch-like network of ducts that converge at the nipple
Some medications can also cause nipple discharge.

These include:
Use of the drugs cocaine and marijuana can also cause nipple discharge.
Generally, if you're not pregnant and your nipples are discharging fluid, you need to see your doctor.
How doctors treat causes of nipple discharge
Your physician will give you a clinical breast exam, ask about your personal medical history, and probably order a mammogram and ultrasound to look for the source of the discharge. Ultrasound is very useful at evaluating causes of nipple discharge. Your physician may also order a ductogram, which involves the instillation of dye into the discharging duct to visualize the interior. In some cases, a biopsy will be performed. For patients who are not pregnant but do have a copious milky discharge from both breasts, blood will be drawn to measure prolactin levels.
Johns Hopkins Hospital Medical News Today
Also read: 7 Causes of itchy breasts all women should know