A bleeding nipple is usually caused by something benign, and roughly 97% of all nipple discharge turns out to be noncancerous. That said, bloody discharge does warrant attention because it carries a higher association with breast cancer than other types of discharge. The most common culprits range from simple friction injuries to small growths inside the milk ducts, and the cause often depends on your age, whether you’re breastfeeding, and whether the bleeding comes from one breast or both.
Friction and Surface Injuries
The simplest explanation is physical damage to the nipple itself. If you’re a runner or do other repetitive cardio, you may be dealing with what’s sometimes called “jogger’s nipple.” Each stride shifts your clothing slightly across your chest, and over the course of a long workout, that constant rubbing can crack the skin and cause bleeding. This is especially common in cold or dry weather when skin is already less flexible.
Prevention is straightforward: place adhesive bandages over your nipples before a run, wear a well-fitting sports bra or compression shirt, or apply petroleum jelly or an anti-chafe balm to eliminate friction. If you’re already dealing with cracked skin, keeping the area clean and moisturized usually resolves it within a few days.
Nipple piercings, rough sexual contact, or irritation from a poorly fitting bra can also cause surface-level bleeding that heals on its own once the source of trauma stops.
Bleeding While Breastfeeding
If you’re nursing, the most common reason for a bleeding nipple is cracked skin from a poor latch. When a baby doesn’t take enough of the areola into their mouth, the nipple bears concentrated pressure and friction, leading to fissures that bleed during or between feedings. A lactation consultant can help correct the latch, and keeping nipples moisturized between feedings speeds healing.
A less common but harmless cause is “rusty pipe syndrome,” where breast milk comes out pink, orange, or rust-colored during the first days after delivery. This happens because the rapid growth of milk-producing tissue creates a fragile network of tiny blood vessels that break easily. The name comes from how the milk looks, resembling water from an old rusty pipe. It typically clears up within three to seven days, though it can occasionally persist for a few weeks. If bleeding lasts longer than a week, further evaluation is a good idea to rule out other causes like a papilloma inside the duct.
Mastitis, an infection of the breast tissue, can also cause bloody or discolored discharge alongside pain, swelling, warmth, and sometimes fever.
Intraductal Papilloma
The single most common cause of spontaneous bloody nipple discharge (when there’s no obvious external injury) is an intraductal papilloma. These are small, wartlike growths that develop inside the milk ducts, usually near the nipple. They’re noncancerous.
Papillomas are most common in people between ages 35 and 55, particularly around perimenopause. The classic presentation is clear or bloody discharge from one nipple, sometimes triggered by pressing on a specific spot near the areola. You may or may not feel a small lump. Treatment involves surgically removing the affected duct, and outcomes after removal are excellent.
Mammary Duct Ectasia
Duct ectasia is another benign condition, most often seen in perimenopausal women between 45 and 55. The milk ducts beneath the nipple widen, become clogged with debris, and may get inflamed. This can produce a thick, sticky discharge that’s sometimes greenish, brownish, or blood-tinged. It’s more common in smokers and in people with inverted nipples.
Many cases resolve without treatment. When symptoms are bothersome or persistent, the affected duct can be surgically removed.
Paget’s Disease of the Breast
Paget’s disease is a rare form of breast cancer that starts in the nipple itself. It’s worth knowing about because its early signs mimic eczema, which can delay diagnosis. Look for flaky, scaly, or crusty skin on the nipple that doesn’t heal with standard skin care. Other signs include itching, a burning sensation, straw-colored or bloody discharge, and a nipple that starts to turn inward. Symptoms almost always affect one breast only and gradually spread from the nipple outward to the areola.
Because it can look like a simple skin rash, any eczema-like change on the nipple that doesn’t improve within a few weeks deserves medical evaluation.
How Bloody Discharge Relates to Cancer Risk
Bloody nipple discharge is more concerning than clear or milky discharge, but most cases still turn out to be benign. A meta-analysis of over 3,100 women with nipple discharge found that about 25% of those with bloody discharge were eventually diagnosed with cancer, compared to about 12% of those with non-bloody discharge. However, other studies have found malignancy rates as low as 5% in the same scenario. The wide range reflects differences in which patients were studied and how they were selected.
The key takeaway: bloody discharge raises the statistical likelihood enough that it should always be evaluated, but the odds still favor a benign cause.
What Testing Looks Like
Evaluation typically starts with a physical exam, followed by a mammogram and ultrasound with close attention to the area directly behind the nipple. Mammography alone catches only about 20 to 25% of the lesions that cause nipple discharge, because these growths tend to be small, sit inside the ducts, and don’t contain the calcifications that show up easily on imaging. Ultrasound picks up what mammography misses in many cases.
If both come back normal but the discharge persists, your doctor may recommend a ductogram (where contrast dye is injected into the duct to map it on X-ray) or breast MRI, which is highly sensitive for both benign and malignant lesions near the nipple.
Signs That Need Prompt Evaluation
Bleeding from the nipple should be assessed by a healthcare provider when it’s spontaneous (happening without squeezing or physical irritation), comes from only one breast, or persists for more than a week or two. Certain accompanying signs raise the urgency:
- A lump or thickening in the breast or underarm area
- Skin changes like dimpling, puckering, or a texture resembling an orange peel
- Nipple changes such as sudden inversion, crusting, or a rash that won’t heal
- Swelling or pain near the collarbone or in the armpit, which can indicate enlarged lymph nodes
- A change in breast shape or size that’s new and unexplained
Discharge that comes from both breasts, appears milky or clear, and only happens when you squeeze the nipple is far more likely to be hormonal or related to medications like oral contraceptives, certain antidepressants, or blood pressure drugs. This type is almost always benign, though it can occasionally point to a thyroid issue or a benign pituitary growth that raises prolactin levels.