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Why Mastitis Is Common in Moms with an Oversupply of Breast Milk

Mastitis is an infection that develops in breast tissue. It can cause a sudden high fever, breast pain, body aches, and chills. Unfortunately, it is common in breastfeeding moms, especially those with an oversupply of breast milk. Infected breasts can feel warm to the touch, look red or blotchy, and feel very painful. Because lactating breasts have so much blood flow, symptoms of mastitis can come on suddenly and spread quickly to the rest of the body. Mastitis should never be ignored. In some cases, it can even turn into a breast abscess that may need to be drained by your OB/Gyn doctor.

Mastitis is more common in moms with an oversupply of breast milk, occurring in nearly 30% of them. Mastitis self care is important. If you have an oversupply, it’s important to know how to manage your supply so you can avoid mastitis. In this article, we will discuss oversupply and the common factors that can lead to mastitis. 

What is an Oversupply?

Before we go into the factors that cause mastitis, let’s discuss oversupply.

The amount of milk a given mom can make varies widely, with low and oversupply on opposite ends of the spectrum. While there is no specific definition of oversupply, it generally means a mom produces more milk than her baby needs. It can include a faster letdown, increased milk flow, a large volume of milk, or a combination of all three.

Because it isn’t possible to directly measure how much milk you have in your breasts at any given time, you have to look for indirect signs. Oversupply can cause leaking milk between feedings, frequent bouts of engorgement or plugged ducts, and/or feeling like your breasts are always overfull. Your baby may also struggle to manage the flow and choke or cry during feedings.

What Are The Factors That Can Lead to Mastitis?

Incomplete Breast Emptying

Maintaining the right amount of breast milk can be tricky when you have an oversupply. It’s crucial to find the right balance – empty your breasts regularly enough to prevent engorgement, but not too often so you don’t increase an already ample supply. On the other hand, if you leave too much milk behind, that backed-up milk can be a delicious breeding ground for bacteria.

If you have oversupply, it’s important to keep a careful eye on how full your breasts are to avoid issues like engorgement and plugged ducts, which can also lead to mastitis. 

Breast Engorgement

In the early days of breastfeeding, oversupply can lead to engorgement, a condition where increased blood flow makes the breasts firm and compresses the milk ducts. This makes it harder for your milk to flow out and drain properly. It can also cause breast pain, low-grade fever, hardness, redness, and warmth.

If your breasts stay engorged, it could mean your baby isn’t emptying them during nursing, you’re producing a lot of milk, or you’re not pumping enough. Left unaddressed, engorgement can lead to plugged ducts or mastitis. 

Nipple Damage

Nipple damage is common when breastfeeding and pumping. It happens because of friction on your nipples from a shallow latch or poorly fitting pumping flanges. If you suffer from nipple damage and also have an oversupply, you can have an increased risk of mastitis. Nipple damage allows bacteria to enter the bloodstream. Since breast milk is so rich in nutrients, it provides an easy setting for bacteria to grow quickly, increasing the chance of infection.

If you’re dealing with ongoing nipple pain, it’s important to figure out the underlying cause. Check your baby’s gape and latch and make sure your pump flanges fit well.

Frequently Asked Questions

What happens when you have an oversupply of breast milk?

Having an oversupply means that you have a faster letdown, increased milk flow, a large volume of milk, or a combination of all three.

Can you get mastitis from feeding too much?

That depends. As long as your baby is nursing efficiently, emptying your breasts, and not causing nipple damage, the removal of milk should help prevent mastitis – not cause it. Mastitis often happens when you don’t empty your breasts fully enough, and/or nursing or pumping causes nipple damage.

How does mastitis affect milk production?

Mastitis can cause the milk-making factories in your breast to break down. For some women, even one bout of mastitis can decrease production.

Can oversupply cause mastitis?

Oversupply may make it more likely to get mastitis if you don't regularly empty your breasts. If you have nipple trauma and oversupply, that chance increases even more.


Mastitis is a common concern for moms dealing with an oversupply of breast milk. Early intervention and management are important to avoid complications. If you experience symptoms of mastitis, seek immediate medical care. 

If you want more medically-based, doctor-created, patient-tested information on breastfeeding, check out Better Breastfeeding’s interactive platform. You’ll get 24/7 access to content and solutions to help you effectively feed your baby, whether you’re breastfeeding, pumping, or both.

Reviewed by Linda Dahl, MD


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