By Ali Weatherford

Even when breastfeeding starts smoothly, or when you overcome some obstacles to get it figured out and things are working well, there can be new issues that come up. This doesn’t necessarily mean that you are doing anything wrong! Two common problems that can crop up for breastfeeding parents are blocked milk ducts and mastitis. These issues can be minimal, but can also bring pain and discomfort. When not handled properly can be big obstacles to breastfeeding.

What is a blocked, clogged, or “plugged” milk duct?

Blocked milk ducts happen when the milk isn’t flowing smoothly through one or some of your milk ducts. You actually have a lot of milk ducts, so having a blocked duct doesn’t mean that the milk flow stops!

A blocked duct happens when there is irritation and inflammation. It’s not that something is lodged in the duct creating a blockage. There is nothing that needs to be removed! Swelling causes the passage for the milk to narrow which can lead to congestion and pressure. When this happens, you’ll probably notice an area that is swollen and tender on your breast.

It can be tricky to know what is causing a lump or pain in the breast. Some level of lumpiness is normal, especially when you’re getting started with breastfeeding. In the first few days after birth it’s normal to start producing a lot more milk, and that can lead to engorgement. Engorgement can also happen if you go longer than usual in between feedings. When engorged, your breasts might get larger, fuller, more firm, and even “lumpy”.

Engorgement can also be uncomfortable, but it’s usually the whole breast that gets sore, and most likely on both sides. While engorgement can sometimes cause a blocked duct, it’s not the same thing. Remember, engorgement is usually felt everywhere, while a blocked duct will feel more like one specific spot on one breast that is swollen and painful.

October is Breast Cancer Awareness Month

This is a great reminder to do regular self-checks of your breasts. When you do these regularly, you’re more likely to know what kind of lumpy is normal for you and you’ll be able to identify anything abnormal.

Because of the threat of breast cancer, it’s important to learn about what is normal, get to know your breasts well, and get any new lumps checked out. It’s important to bring this up when discussing blocked ducts and mastitis because they can sometimes be misdiagnosed. In my personal life, I’ve had two friends have new lumps diagnosed as blocked milk ducts because they were breastfeeding, only to find out later that it was actually breast cancer. It does happen, so don’t dismiss it. Get checked out.

But, it’s also important to remember that there are MANY weird and lumpy breast issues that are NOT caused by breast cancer and are pretty harmless. Blocked ducts are one of those things. Blocked ducts are usually easy to diagnose, and a lactation consultant can often help with that. A blocked duct should change or go away pretty quickly. It will probably look and feel better or different AFTER your baby feeds from that breast. If you manage it well, it will likely be gone in just a couple of days or at least within a week.

If the area is not responding like this, or if you develop worse or new symptoms, it might not be a blocked duct. Your lactation consultant should be able to help you diagnose and treat normal breastfeeding related issues. If they note that something different is going on, they should refer you to another specialist. But also, use your intuition! If something feels wrong, it’s best to get it checked out.

Causes of Blocked Milk Ducts

Some people are just more likely to have blocked ducts, but most of the time it’s caused by a situation that you can do something about.

One of the most common causes is an oversupply of milk. Some people just make more milk than the baby can drink. Most of the time this is a temporary problem that can occur when you are first establishing your milk supply. You can manage or prevent this by avoiding any more breast stimulation than necessary for feeding your baby during that time. If you are pumping, avoiding that for a while might help. The more you ask your breasts to deliver milk, the more milk your body makes. This can make an oversupply problem worse.

Sometimes blocked ducts happen because your breasts are not being fully emptied during feedings or pumping sessions. If milk stays in your breast , it can lead to congestion and cause a blockage.

  • Minimizing pumping might help. Pumps are not usually as effective at emptying the breast as a baby.
  • Sometimes the baby has trouble fully emptying the breast.
    • If this is because you have an oversupply of milk, it might just take a little time for that to regulate after you stop over-stimulating your breasts.
    • Or if it’s in your early days of breastfeeding, some adjustment time is normal. In the meantime, you might switch to a feeding pattern where you only offer your baby one breast each time. You might start with the side with the blocked duct. This may help your baby completely drain the breast each time and eventually things will even out.
    • There could be a problem with the baby’s latch or suction strength. Sometimes babies can’t hold on to the breast correctly, or don’t have the strength to fully empty the breast. A lactation consultant should be able to help you figure out if this is the problem and offer ways to correct it.

Blocked ducts can also be caused by some physical damage to the breast tissue. If you’re regularly wearing something tight on your breasts, it can cause blocked ducts. This can be caused by a seat belt, the strap of a heavy purse or bag, or even a tight bra. This kind of pressure on the milk ducts can cause inflammation and lead to a blockage.

How can you treat a blocked duct? Breastfeeding Success has this How-to Guide to help you.

What is mastitis?

Mastitis is sort of a general term for breast swelling and tenderness. A lot of times mastitis is caused by a blocked milk duct. When the blockage is not addressed, it can lead to increased damage, so it’s best to catch problems quickly and get help from a lactation consultant (IBCLC).

Most people will notice swelling and tenderness on a particular area of the breast. If you have lighter skin, you might also see some redness in the area, but if you have darker skin, you might not. Remember, if your breasts are swollen all over and tender, this might be engorgement.

If you have a fever, chills, body aches, and fatigue along with the breast swelling and tenderness, please see an IBCLC right away, and also a doctor. An IBCLC is a lactation consultant trained in the clinical management of breastfeeding. They can help figure out the cause and will likely refer you to a doctor for management of the infection if you haven’t seen one already.

Causes of Mastitis

As mentioned above, mastitis is a sort of general term to describe the problem of having breast swelling and tenderness. There are many causes including:

  • Blocked ducts are a leading cause, so refer to the top of this article for the causes of blocked milk ducts to help you prevent and treat mastitis.
  • Infection. If you have cracked nipples or sores on your breast, bacteria can enter the breast tissue and cause an infection.

Blocked milk ducts and mastitis are common hurdles for breastfeeding parents, but fortunately these issues can be prevented or easily treated, especially if you catch it early. If you’re recovering from an infection or severe mastitis, take it easy. Get plenty of rest, fluids, and continue to breastfeed on a normal schedule. Your lactation consultant will also probably offer some great tips to keep you more comfortable so you are able to continue breastfeeding.


How to do a breast self-exam

What to know about breast lumps

Academy of Breastfeeding Medicine Clinical Protocol #36: The Mastitis Spectrum, Revised 2022. BREASTFEEDING MEDICINE Volume 17, Number 5, 2022 ª Mary Ann Liebert, Inc. DOI: 10.1089/bfm.2022.29207.kbm

ABM Clinical Protocol #30: Breast Masses, Breast Complaints, and Diagnostic Breast Imaging in the Lactating Woman. Breastfeeding Medicine, 14(4), 208–214.
Zhao, C., Tang, R., Wang, J., Guan, X., Zheng, J., Hu, J., Hu, G., & Song, C. (2014). Six-Step Recanalization Manual Therapy. Journal of Human Lactation, 30(3), 324–330.

Our articles are not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment.

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