An illustration of a parent pumping milk with a breast pump.
January 3, 2023
By TLN

What you need to know about clogged milk ducts

Clinically reviewed by: Demi Lucas, IBCLC
Last updated: November 12, 2024

Clogged milk ducts, also called plugged or blocked milk ducts, are hard lumps or knots in the breast that are tender to the touch. Up to 20 percent of parents experience clogged milk ducts, and with the support of your International Board Certified Lactation Consultant (IBCLC), you’ll be back to pain-free feedings in no time. We consulted Chrisie Rosenthal, IBCLC, PMH-C, for more information about clogged milk ducts.

Causes of clogged milk ducts

Clogged ducts occur when milk flow is obstructed, causing pressure to build behind the duct and irritate the tissue around it. Several issues can cause a blocked duct, including engorgement, skipping or missing feedings, oversupply, or consistent pressure on the same area of the breast.

Engorgement. If you regularly skip feeds, or go for an extended period of time without removing milk from the breast, it can lead to feeling “overfull,” which is referred to as engorgement and can cause clogged ducts. Some parents experience engorgement when their baby starts sleeping longer stretches at night.

Oversupply. Parents who have an oversupply of breastmilk are at a higher risk for plugged ducts.

Pressure. A diaper bag strap, car seat belt, and even a bra that’s too tight can put pressure on your chest and lead to plugged milk ducts.

On the bright side, many of the causes of clogged ducts are preventable. Rosenthal says, “Frequent, and effective milk removal is the best insurance against plugged ducts.” Make sure you’re not skipping feedings, feeding regularly, and avoiding unnecessary consistent pressure on your chest.

Symptoms of clogged milk ducts

You can think of a clogged milk duct as a breast milk traffic jam. Clogs typically appear suddenly and are most often localized in one breast at a time. Typical symptoms of clogged ducts include…

  • A hard lump in your breast, which may be red and sore or tender to the touch
  • Engorgement or swelling in the breast
  • Shooting pains in the breast
  • Pain during letdown (the initial flow of milk)
  • After nursing or pumping, the lump may move or get smaller
  • Physical discomfort may lessen after feedings
  • A milk bleb, also known as a milk blister, on the nipple
  • Decreased supply or pumping output

Clogged milk ducts vs. mastitis

While clogged ducts and mastitis symptoms are similar, they are not the same. When left untreated, a clogged duct that doesn’t clear can lead to breast infections (mastitis). Mastitis is marked by flu-like symptoms, swelling, joint pain, fatigue, and redness around the affected area of the breast. If you are experiencing mastitis symptoms, contact your physician. 

Clogged milk ducts vs. breast cancer

Both clogged ducts and cancerous lumps can manifest as lumps on the breast. So how can you tell the difference? Rosenthal says, “A plugged duct typically appears suddenly, and is usually tender and painful. It may come and go over time, and change in size and tenderness as you work on clearing it. If you have a lump that’s firm, painless, and doesn’t change over time, it’s best to reach out to your doctor.” If you do feel a lump in your breast, don’t panic. There are many explanations for lumps in the breast, but it’s always a good idea to have it checked out, if for nothing else than your own peace of mind. 

How to treat clogged milk ducts

While some plugged ducts may resolve away on their own, most will require additional measures. Your IBCLC will help you identify the underlying cause of the clog, the best treatment method for you, and together you can make a plan to prevent future clogs. In the meantime:

  1. Don’t stop breastfeeding. Continue to breastfeed frequently to keep your milk flowing. Favor the affected side as much as possible. Babies tend to suck stronger and more vigorously on the first side offered.
  1. Check your baby’s latch. If your baby isn’t latching correctly, they won’t be able to efficiently remove milk from the breast which can lead to plugs. Talk to your IBCLC if you have questions or concerns about your baby’s latch. 
  1. Experiment with different breastfeeding positions and techniques. You can try positioning your baby’s nose or chin toward the plugged duct, which may help clear the clog. Some parents find dangle nursing or pumping helpful. To use this technique, position yourself on your hands and knees over your baby while feeding or while pumping with pump flanges pointed downward.
  1. Gently massage. When feeding or pumping, integrate a gentle breast massage, focusing on the affected breast. Using warm water before or during the massage on the affected breast could also help.
  1. Express milk. When you have a clogged duct, it’s important to restore milk flow, and various techniques involve extra pumping or milk removal. Be careful not to over-do it though. According to Rosenthal, “Depending on the parent’s supply, extra milk removal can lead to oversupply which puts the parent at increased risk for plugged ducts and mastitis.”
  1. Talk to an IBCLC. Clogged ducts can lead to mastitis if left untreated. Talk to your IBCLC in order to address the issue and make a plan to prevent future plugs. 

How will you know when the clog is gone? Rosenthal says, “Most parents say they know that they have cleared it. They may report that they see the plug, experience a ‘rush’ of milk and an increase in volume, or the pain resolves.” 

It’s also best it’s best to avoid these commonly recommended treatments that are not clinically sound: 

  1. Heat — exacerbates inflammation which can make clogs worse. 
  2. Aggressive massage/vibration  — commonly recommended but worsens inflammation and can prolong recovery or treatment. 
  3. Lecithin supplements — not enough research to support this as a blanket treatment across the board, and individualized guidance from one’s IBCLC is recommended before using a supplement. 
  4. Significantly changing one’s pumping/feeding routine — abrupt changes can affect milk supply and place additional pressure being put on the ducts while recovering. Drastic changes in feeding or pumping routines may not be helpful in the recovery process. Your IBCLC can recommend the best course of action!

The breastfeeding journey is full of ups and downs, and clogged milk ducts are no one’s favorite part. But with awareness and the support of an IBCLC, you can work through them. If you’re still struggling to clear the clog or you continue to have recurring issues with clogged ducts, talk to a TLN IBCLC to uncover the root of the problem and create a plugged duct prevention plan. 

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A parent lies in bed while holding an infant, with an International Board Certified Lactation Consultant offering support.