Why Does My Breast Milk Smell Like Vomit?

breastmilk smells like vomit

Motherhood comes with a lot of worries. If your breast milk smells like vomit, you may be wondering whether it’s safe to feed this smelly milk to your baby.

There are various reasons why milk can have a sour or rancid smell; many moms have witnessed different scents of their breast milk.

Read on to find out what causes smelly breast milk and if it’s safe to feed your baby. 


What causes breast milk to smell like throw up?

Your breast milk smells like vomit because of excess lipase, chemical oxidation and poor storage. Let’s look into this in detail and see whether it is safe to feed your baby smelly breast milk.

Below are the possible causes for breastmilk smelling like cheese:

High lipase activity in mom’s milk

Lipase is an enzyme present in breast milk; it assists your baby in digesting the milk and absorbing the necessary nutrients from it. If your breast milk has excess lipase, it can change flavor within 24 hours or a few days.

High lipase activity may quicken the breakdown of fats in the milk when you store expressed milk even under cool temperatures, causing a change in its taste and scent.

High lipase does not affect the baby if they drink this stored milk or nurses straight from the breast.

However, some babies will reject stored milk with a different odor and taste; thus, a solution will be required to make the milk more palatable.

READ ALSO: What Happens If Baby Drinks Spoiled Breast Milk

breastmilk smells like vomit

Mom’s Diet

Breast milk can smell like vomit when chemical oxidation occurs after the mother consumes polyunsaturated fat or drinks water that contains iron or copper ions. Various other foods and medications will affect the taste of breast milk.

Changes in milk that result from the breastfeeding mom’s diet will affect stored milk and fresh milk that is being suckled directly from the mother.

Breastfed babies enjoy a wider variety of food sooner than formula-fed babies because of their prior exposure to different food flavors through breastmilk.

How the expressed milk is stored

If you store breast milk for long before refrigerating it, the lipase activity will increase, causing it to become sour much quicker. Milk tends to separate when left standing as the cream rises to the top of the container.

When the container is not tightly closed, milk will also become sour fast as it can absorb other strong smells of flavors present in the fridge.

Storing milk in containers that have not been cleaned thoroughly or using a poorly cleaned breast pump will give breastmilk an off-taste and smell. Breastmilk is susceptible to impurities, and any slight sign of them will alter the state of the milk to sour.

READ ALSO: How To Get Breast Milk Fat Off The Sides Of Bottles


High breast pump speed and pressure

Some mothers say their breast milk smelled like cheese and was foamy when they used their breast pumps at higher speeds, but the scent improved after reducing the pumping rate.

READ ALSO: Why Is My Breast Milk Foamy When Pumping?

How to tell breast milk is contaminated

Generally speaking, there is no need to worry if you follow the breastmilk storage guidelines religiously. Nonetheless, to guarantee your baby’s safety, check that your breast milk does not smell fishy – this is the most common symptom. 

Other signs of stale milk include chunkiness and tasting bitter as sour cow milk would.

breastmilk smelling like cheese

Breast milk smells like vomit? Here is what to do

1.      Reduce lipase in breast milk by scalding the milk

The most common way is to prevent a soapy smell in milk is to scald the fresh milk. Here’s how to scald breast milk quickly;

Heat the milk in a pot until you see tiny bubbles forming around the pot’s edges. It must not boil; otherwise, you will kill nutrients in the milk. Scalding will prevent enzymes from digesting the milk fast. Cool the milk quickly, preferably in ice, and then you can store it in the fridge.

NB: Some important nutrients will also be lost in the process.

2.      Make sure to clean all utensils that will come into contact with the breast milk meticulously.

3.      Mix the refrigerated milk with fresh milk for older babies to restore it to its original flavor. If  your baby is taking solids, then you can mix the milk with other foods to trick your baby into accepting it.

4.      Watch your diet and try to avoid rancid fats such as fish oil and increase your intake of beta carotene and vitamin E, which are antioxidants.


Breast milk has numerous benefits for both mother and baby. It encourages bonding between mother and child while ensuring that the baby gets vital nutrients.

Ensure that the milk is in its best form and free from various odors to keep the baby well fed. If your breast milk smells like vomit, try the above mentioned tips and tricks.


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