Causes of Clogged Milk Ducts

Clogged, or plugged, milk ducts are a common problem that many breastfeeding people experience. Narrowing and inflammation of the milk ducts reduces milk flow which may feel like the milk is plugged up. The condition can get worse when milk production is overstimulated by excessive pumping.

In most cases, the inflammation can be managed with home treatments with ice packs and nonsteroidal anti-inflammatory drugs (NSAIDs). But if the plugging doesn't go away with proper treatment, it may signify a more serious condition, such as mastitis or, in rare cases, breast cancer.

This article discusses the causes of plugged milk ducts, how they are treated, and when to see a healthcare provider.

Signs of a Plugged Milk Duct From Breastfeeding

A plugged milk duct may feel like a sore, tender lump in the breast, even though there is no actual lump or plug. Although it was once thought that the milk ducts became "plugged" up, further research determined that when milk ducts become inflamed, this causes them to narrow and restrict milk flow. Inflammation can be made worse by attempting to completely "drain" the breast milk by overpumping.

Signs and symptoms often occur in one breast at a time. They may include:

• Breast tenderness
• An area that feels like a lump the size of a pea or larger
• Heat and redness
• A small white spot on the nipple tip
• Decreased milk supply in one breast
  

Causes of Non-Breastfeeding Related Blocked Ducts

Although more common among breastfeeding individuals, blocked milk ducts may also be caused by conditions other than nursing.

Mammary Duct Ectasia

Mammary duct ectasia is a noncancerous (benign) breast condition that occurs when a milk duct beneath the nipple widens and thickens. This can cause the milk duct to become blocked, leading to fluid accumulation and sticky, thick nipple discharge.

It may cause symptoms like tenderness around your nipple area and inverted nipples. Mammary duct ectasia may affect a single breast or both breasts and is more common among women nearing menopause.

Intraductal Papillomas

Intraductal papillomas are noncancerous tumors that grow within the milk ducts near the nipple. They can cause clear or bloody nipple discharge and can form a painful lump. The papillomas may also be found further away from the nipple in groups.

Mammography, ductography, MRI, and sonography can all be used to detect and diagnose breast papillomas. The specific cause of intraductal papillomas is not known. Your provider will likely recommend imaging such as a mammography, ultrasound and/or MRI to detect the papilloma.

You may still be able to breastfeed but there may be pain and your medical provider may advise against it if you are having discharge.

Periductal Mastitis

Periductal mastitis is a noncancerous inflammatory breast condition that often occurs in young women who are not breastfeeding. Symptoms include nipple discharge, a breast lump, and breast tenderness.

While the exact cause remains unknown, some clinical evidence suggests obesity, diabetes, bacterial infections, and smoking may cause the condition.

Ductal Carcinoma In Situ and Invasive Ductal Carcinoma

Ductal carcinoma in situ (DCIS) is an early form of breast cancer that affects the cells of the milk ducts in the breast. DCIS doesn't spread outside the breast but should be treated because it can develop into invasive breast cancer that extends beyond the milk ducts.

Although it does not typically come with signs and symptoms, DCIS may cause bloody nipple discharge, a lump, or itching in some people.

Invasive ductal carcinoma (IDC) is the most common type of breast cancer, according to the National Breast Cancer Foundation. It forms in the milk duct and can also block milk from flowing.

Mastitis vs. Plugged Ducts

Mastitis is a spectrum of conditions that begins with inflammation or plugging of the milk ducts. Most plugged ducts can get resolved on their own within a few days. If the inflammation worsens, it can lead to inflammatory mastitis and more seriously, acute bacterial mastitis.

Symptoms of mastitis are similar to those of a plugged duct. However, mastitis is often accompanied by more severe symptoms, including:

• Redness, warmth, and swelling of the breast (may be wedge-shaped)
• Breast pain
• Body aches, fatigue, nausea, vomiting, chills, and other flu-like symptoms
• A fever over 100.9°F
• Discharge from the nipple

Home Remedies

The Academy of Breastfeeding Medicine provided new guidelines for breastfeeding in 2022 to reduce the chances of inflammation and mastitis. They caution that you should NOT drain the milk when breastfeeding or pumping, as this can cause hyperlactation which contributes to the inflammation. Pumping too often can also cause breast trauma, and should be limited to only a small volume. They also found that traditional treatments such as using warm compresses and massage worsen the condition.

Remedies to help clear a blocked duct and ease pain and swelling include:

• Keeping your nipples dry and avoiding nipple pads that prevent air drying and may grow bacteria
• Positioning your baby with their tongue and chin pointing toward the clogged duct to maximize drainage to the area
• Avoiding deep massages of the breast
• Applying a cold compress or ice to reduce inflammation
• Avoiding heat applications
• Getting adequate rest
• Taking over-the-counter (OTC) pain relievers, such as Advil (ibuprofen) or Tylenol (acetaminophen)
• Wearing a supportive bra
• Staying hydrated by drinking plenty of water and other clear fluids

When to See a Healthcare Provider

If you experience painful, swollen breasts accompanied by chills, body aches, or a fever, contact a healthcare provider as soon as possible. Many cases of mastitis require antibiotics to treat the infection. If left untreated, mastitis may destroy breast tissue, resulting in an abscess that must be drained.

If symptoms continue for seven to 10 days after antibiotic treatment, a healthcare provider may recommend imaging or a biopsy to test for inflammatory breast cancer, which can cause symptoms similar to mastitis.

Summary

Clogged milk ducts are painful and can make breastfeeding a challenge. In most cases, a clogged duct can be treated at home using simple remedies. However, clogged milk ducts may progress to an infection called mastitis or be a sign of a more severe condition, like breast cancer.

If the lump on your breast changes size or does not go away after a few days, or if you develop a fever, chills, or nausea, it is important to contact your healthcare provider immediately for further evaluation and treatment.