Breastfed Baby Allergies: Signs, Causes & Treatment

breastfed baby allergies

Baby Allergic To Breast Milk?

Are you concerned your baby has a breast milk allergy? Wondering if it’s even possible for your baby to be allergic to breast milk? 

Good news is usually they aren’t… but there are some things you could eat that may cause a problem. 

We’ll go over all you need to know about breastfeeding a baby with allergies. 

baby allergic to breast milk

Can Babies Be Allergic To Breast Milk?

Babies can’t really be allergic to breast milk itself. Mom’s milk is made perfectly for her baby, and it actually protects from allergies. 

But babies can be allergic to things that find their way into breast milk. 

How does that happen? 

Through mom’s diet. 

When a breastfeeding mom eats something that her baby is allergic or sensitive to, her baby may have a reaction. 

The good news is that cutting out the allergen from mom’s diet will usually solve the problem for her baby. 

Normal Baby Fussiness

Before we go on, let’s talk about normal baby fussiness. 

The average length of time a baby cries every day is 2.5 hours! So just because your baby is fussy and crying doesn’t necessarily mean there’s a food problem. 

Babies tend to become more fussy around the 2-3 month mark, and then the fussiness starts to subside. But moms worry when a usually sleepy, happy baby grows more and more fussy.

Often, babies are fussy because they’re overstimulated, figuring out their sleeping routine (and figuring out life!), or just want comfort. 

Additionally, some babies are colicky and there’s no reason for it. Colic is a very difficult thing to manage, but know that when there’s no cause that’s all you can do… manage it. 

One of the best ways to calm your fussy baby is to nurse them and spend time cuddling. For newborns especially, it might seem like that’s all you do. Again that’s normal and doesn’t necessarily mean your baby is experiencing problems. 

Allergies are actually not as common as people think. In the instances that a baby experiences allergy problems while breastfeeding, it’s usually due to one of the most common allergens. Those include dairy, soy, nuts and eggs. 

But the most common allergen is dairy, or a milk protein allergy. 

Milk Protein Allergy Breastfeeding

If there is an allergy, the most common culprit is milk protein. Not from your breast milk, but from milk you drink in your diet (like cow’s milk). 

It’s different than lactose intolerance. Mom’s milk actually has lactose in it and babies are made to digest their mom’s lactose. Generally it isn’t lactose intolerance that causes the problem. 

When a mom drinks cow’s milk, the proteins enter her blood stream. Within 30 minutes, that blood brings fluids to help make breast milk. The milk proteins enter the breast milk and can cause problems for the baby. 

Drinking lactose-free milk won’t help because lactose isn’t the problem. Lactose-free milk still contains milk proteins and can still contribute to allergies. 

Goats and sheep milk both contain very similar proteins, so if there’s a problem it’s best to cut out milk altogether. 

The next most common allergen is soy. Babies react to soy protein similarly to cow’s milk protein. Often babies are allergic to both. 

milk protein allergy breastfed baby allergies

Signs Of Milk Allergy In Breastfed Baby

These are the signs and symptoms of an allergy in a breastfed baby: 

  • spitting up or vomiting
  • abnormal fussing
  • excessive and smelly farts
  • slimy, green or bloody poop
  • ezcema or rashes
  • hives or swelling

Generally these signs show up between 4 and 24 hours of mom eating the allergen. It can be present in the breast milk in as soon as 30 minutes. It can also stay in the breast milk up to 2 weeks! 

Hives or swelling are the most obvious and severe sign, they should be taken very seriously. 

For the other signs, many of them are normal in breastfed babies. Babies spit up, have slimy and discolored poops occasionally, and tend to fuss. 

They are babies. 

The important thing is to pay attention to your baby and what their normals are. If you notice anything different after eating specific foods there may be a problem. 

Food Allergies In Breastfed Babies

If you notice any of the above symptoms, try to pay attention to what you ate before the onset. 

For babies with allergies, most symptoms are manifested through the GI tract. When babies are very young, their intestines are immature and allow particles to pass through. 

There is a difference between a sensitivity and an allergy. Sensitivities are uncomfortable but generally not severe. Allergies are more severe and cause inflammation in the body. 

Eczema can be a reaction in the body to an allergen. If you start to notice eczema or rashes after eating something different (or eating a lot of something), your baby may have an allergy to that food. While food allergies can go away, be cautious when starting your baby on solids if they react to anything you eat through breastmilk. 

Baby Food Allergy Treatment

If you suspect that your baby has an allergy, there isn’t a specific way to tell what they’re reacting to. While dairy is the most common allergen, it isn’t always the culprit. 

A family history of food allergies might help determine the cause. If a family member is allergic to a certain food, there’s a higher chance the baby will be too. 

There’s debate about whether or not to prevent eating common allergens late in pregnancy and early breastfeeding. Some experts think that exposure in the womb and through breast milk will improve outcomes. Others believe that it could sensitize them to the allergen and cause a problem. 

The research isn’t clear, so it’s probably best to eat a normal diet UNLESS you notice a reaction in your baby. 

One way to prevent food allergies is to breastfeed exclusively for 6 months. When your baby is 6 months old, their GI tract becomes mature. Before that time, it can allow small proteins through (like cow’s milk proteins). Breast milk encourages healing and is easily digested. So if you are concerned about allergies, it’s a great option to just breastfeed your baby exclusively!

How To Determine What Baby Is Allergic To 

The best way to figure out what your baby is allergic to is to cut the food out of your diet. It takes 1-2 weeks for the food to be completely out of your breast milk and sometimes babies seem worse before getting better. 

Another option is the elimination diet. In this option, you cut out all major allergens (milk, soy, eggs, nuts, wheat) for 2 weeks. Then, slowly introduce one food back into your diet at a time, wait a week, and notice how your baby reacts. When reintroducing foods, start slow because sometimes babies react with large portions but not with small portions. 

Keeping a journal of what foods you eat and how your baby acts might help you figure out what the problem food is. 

Babies can outgrow their allergies anytime between 6 and 18 months (although some don’t). So if you’ve cut something out of your diet, you could try reintroducing it down the road and watch your baby’s reaction. 

Keep Breastfeeding If You Suspect Allergies! 

The best thing you can do if you suspect your baby has allergies is continue breastfeeding! 

Breast milk contains nucleotides, glutamine, lactoferrin and countless other beneficial nutrients! The components of breast milk are healing and promote your baby’s stomach development. It also contains antibodies to help your baby’s body defences. Secretory IgA is an antibody that coats your baby’s intestines and helps prevent proteins from passing through and causing allergies. 

Basically, breast milk has the perfect combination of nutrients and protects your baby from being susceptible to allergies. 

Formula is the nest best thing to breast milk… but it is full of harder-to digest ingredients. That’s why formula-fed baby poop smells worse than breastfed baby poop. Additionally, most formulas are made with either cow’s milk or soy- two of the most common allergens! 

An option is hydrolyzed formula, but babies tend to reject it because of the taste. It’s also very expensive. 

The best option is usually to continue breastfeeding and alter your diet.

If your baby has eczema, you can try adding fish oil into your diet! In this study, when a mom supplemented with fish oil her baby’s eczema disappeared. Then, she stopped taking the oil and the eczema returned. When she started taking it again, the eczema disappeared again! 

Healthy fats are essential for skin health and renewal so while eczema is a sign of allergies – simply adding fish oil might solve the problem! 

breastfed baby allergies and solid foods

Baby Allergies And Solid Foods

If your baby has a history of eczema, they are more susceptible to food allergies. Take this into account when starting solid foods with your baby. 

Introduce one solid food at a time and notice how your baby reacts. Cow’s milk shouldn’t be started until after your baby’s first birthday (use formula or breast milk until then).

If you have a family history of certain allergies and your baby has eczema, talk to your pediatrician about allergy testing. 

Try not to start your baby on solids until 6 months if allergies are a concern to give them the best protection against allergens! 

A Personal Story About Baby Allergies

When my husband was a baby, he stopped breathing twice. 

His parents were terrified. 

Both times, it was after he was exposed to milk. 

So when I had my daughter, I knew that giving her dairy wasn’t an option. However I drank it and breastfed and she didn’t seem to have a problem with that. 

My daughter also had eczema (which is a sign of allergies). 

When she turned 5 months old, my pediatrician suggested introducing peanut butter to her. His theory was that exposure young could help prevent allergies in the future. He also refused to test her allergies because often there are false positives. 

So I gave her a tiny bit of peanut butter. She swelled up, almost stopped breathing, and we spent the following 2 nights in the Emergency Room. 

It was terrifying. 

Allergy testing showed her extremely allergic to nuts, dairy, and eggs. 

I learned later that eczema is a sign of allergies. 

So from personal experience, I can’t stress enough… BE CAREFUL when introducing common allergens if your baby has eczema! 

Personally, I will probably ask to get all of my children allergy tested from now on. 

That’s because of my husband’s severe history and now my daughters. 

Like I said, allergies aren’t as common as most people think… 

But listen to your intuition mama! I knew something didn’t feel right when my pediatrician advised me to introduce nuts. And I’ll never do it again. 

Notice how my daughter didn’t have a problem with my breast milk even though I was drinking dairy. I can’t explain that… but any time a drop of milk touches her skin, a welt immediately shows up. Our breasts do filter our blood, so some babies have problems and others don’t (even if they do have food allergies).

Each baby is different so it’s up to you to recognize how your baby acts and reacts to things! Don’t be afraid to test out different things in your diet, and eliminate other things. You know your baby best so you are the best person to determine a problem! 

While some people don’t recommend allergy testing, I don’t think it’s a bad idea (especially with a family history). But if your baby doesn’t have eczema or a family history of allergies, chances are that nothing is wrong! 

Just pay attention to what you eat and how your little one acts. And listen to your gut! You know your baby better than anyone.

Breastfed Baby Allergies: Conclusion

In conclusion, the best way to tell if your baby has allergies to something you’re eating is to watch them carefully! Pay attention to what you are eating and how your baby acts afterwards.

Try the elimination diet if you suspect a problem, but know that allergies are rare. The most common allergy is a cow’s milk protein allergy and babies aren’t allergic to your breast milk itself!

If you have questions or would like to talk to someone about baby allergies please reach out to me! I love helping mommies feed their babies and am always happy to chat.

Kealy Hawk lactation consultant
Kealy Hawk, BSN, RN, CLC

Kealy is a Registered Nurse, Lactation Counselor, and most importantly a mommy! Her own baby feeding struggles gave her a passion to help moms throughout their feeding journey. She specializes in breastfeeding support and evidence-based formula recommendations. To talk with Kealy or take one of her breastfeeding or formula classes, visit

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