Allergies & Food Intolerances in Breastfed Infants

Crystal P.

Updated July 14, 2025 17:11

My baby spits up a lot, is really fussy, and seems colicky. It feels like more than normal—could he be allergic to my breast milk?

That’s a very valid concern—you’re paying close attention to your baby, which is the first step in figuring out what’s going on.

Click here to learn more about your baby’s immature digestive system and other common causes of gas and spit-up. Ruling out common causes is a good first step.

When to Consider a Food Sensitivity

A true allergy to breast milk is very rare and most breastfeeding moms do not need to change what they eat. If a baby does show signs of an allergy or intolerance, it’s usually not the breast milk itself. Instead, it may be a reaction to a food protein in the mom's diet—most often dairy or soy, but sometimes other common triggers like eggs, wheat, or nuts—that pass into the milk.

Exclusively breastfeeding can actually lower your baby’s risk of developing food allergies. Only about 5% of breastfed babies have a negative reaction to something in their mother’s diet. However, the risk goes up with a family history of allergies:

If one parent has a food allergy, the baby’s risk is 20–40%.
If both parents do, the risk rises to 50–80%.

In some cases, symptoms could point to reflux, allergies, or food intolerances. In rare cases, repeated forceful vomiting (especially if it’s projectile) may be caused by a condition called pyloric stenosis. This happens when the muscle at the bottom of the stomach becomes too tight, blocking food from passing into the intestines. It usually shows up in the first few weeks of life and needs medical treatment, so always check with your doctor if you're concerned.

Call Your Doctor if Your Baby:

Seems very uncomfortable when spitting up
Cries or arches before spit-up
Has frequent coughing or choking spells
Projectile vomits large amounts
Spits up blood or has pink/red spit-up
Is losing weight or gaining very slowly

Cow’s Milk: The Most Common Culprit

Cow’s milk protein is the most common trigger in infants with food sensitivities. But each baby is different—not every baby reacts to the same foods. That’s why we do not recommend eliminating dairy from your diet unless necessary. Changing your diet can be difficult and might discourage some moms from continuing to breastfeed, so it's important to confirm that dietary changes are needed first.

Dairy Allergy vs. Intolerance

Dairy Allergy (Immune Response)

This is a reaction by the immune system and is usually more serious—though less common—than an intolerance. It affects about 0.5% to 7.5% of children under 3 and can mimic reflux.

Did you know? One study found that breastfed babies who received formula in the first 24 hours of life were seven times more likely to develop a cow’s milk protein allergy compared to babies who were exclusively breastfed.

Soy proteins are similar to cow’s milk proteins. So babies allergic to one are often sensitive to both.

Common Symptoms of a Dairy Allergy:

Immediate (Severe) Reactions:

- Hives
- Wheezing or coughing
- Itching or tingling around the mouth
- Swelling of the lips/tongue/throat
- Shortness of breath
- Vomiting
- Anaphylaxis (constriction of the airway - seek emergency medical care immediately)

Delayed Reactions:

- Diarrhea
- Blood or mucous in stool (always notify your pediatrician)
- Abdominal pain or cramps
- Runny nose
- Itchy or watery eyes
- Colic
- Constipation

Dairy Intolerance

When people hear “dairy intolerance,” they often think of lactose intolerance. But lactose intolerance—when the body can’t digest the sugar in milk—is very rare in young babies, especially those who are breastfed.

In breastfed babies, it’s more common to have dairy protein intolerance. This is not an allergy. It’s a reaction in the stomach or gut to the protein in cow’s milk. These proteins can pass into breast milk from the foods a breastfeeding mom eats.

Symptoms of Dairy Intolerance:

- Bloating
- Gas
- Diarrhea
- Tummy pain

Suspecting Dairy or Soy Intolerance?

If your baby shows signs of a cow’s milk protein or soy protein intolerance, your healthcare provider may recommend eliminating both dairy and soy from your diet. This can be challenging, but many moms weigh the benefits of breastfeeding versus the difficult diet changes and choose to continue breastfeeding. Most babies outgrow a dairy intolerance by one year of age.

Ask your WIC dietitian how to get enough calcium, vitamin D, and healthy fats without dairy or soy. They will have recommendations on smart substitutions for daily meals.

Watch Out for Hidden Sources of Dairy & Soy

Even when you think you’ve eliminated dairy or soy, they can still hide in everyday foods and labels. Lactaid milk and other “lactose-free” products still contain dairy proteins and should be avoided. You will need to get really good at reading nutrition labels carefully. Dairy and soy can be found in unexpected foods like:

Bread
Salad dressings
Pasta sauce
Baked goods
Processed foods (cereal, chips, cookies, boxed meals, soups)
Restaurant meals

Common dairy terms on labels:

Milk, cheese, yogurt, butter, cream, whey, casein, nonfat dry milk, milk solids, milk chocolate, buttermilk, lactalbumin

Common soy terms on labels:

Soy, soybean, soy protein isolate, soy flour, vegetable protein, textured vegetable protein, tofu, tempeh, miso, soy sauce, broth, soy lecithin, soy starch

How Long to See Results?

Most babies respond to a dairy-free diet within a few days, but it often takes 2-3 weeks for it to fully clear from their system and the baby's reaction to resolve completely. Be patient—changes usually happen gradually.

What If It’s Not Dairy or Soy?

If symptoms continue after removing dairy and soy, your doctor may suggest trying an elimination diet. This means removing other possible food triggers from your diet, one at a time to more easily pinpoint the cause. Common foods to start with include eggs, wheat, nuts, citrus fruits, corn, and fish/shellfish. These are less common triggers than dairy or soy, but some babies may still be sensitive to them.

A pediatrician or WIC dietitian can help you decide which foods to try removing and how long it may take before seeing results. Most babies don’t need all of these foods removed—and many outgrow early sensitivities by their first birthday.

They will also guide you through when and how to reintroduce foods, often starting when baby is 9–12 months old.

Can My Breastfed Baby Be Tested for Allergies?

Allergy testing is another important topic to discuss with your baby’s doctor. Some may recommend allergy testing, but the results may not be as accurate—or could even be misleading—in babies under one year of age.

Skin prick tests and blood tests can sometimes help identify true allergies, but they do not detect intolerances, which are more common in infants. That’s why many doctors consider your baby’s symptoms and may suggest trying an elimination diet first.

What If Baby Needs Formula?

If your baby’s symptoms don’t improve or your doctor suggests pausing breastfeeding temporarily, it’s okay to feel a little overwhelmed or discouraged. Feel empowered to play an active role in your baby’s healthcare, and don’t hesitate to share your questions and wishes with your doctor. Your doctor may suggest a low-allergen/hypoallergenic formula:

Partially broken-down protein formulas:

Similac Alimentum
Enfamil Nutramigen

Fully broken-down protein formulas:

EleCare
Neocate
PurAmino

Talk to your WIC caseworker to see if these specialized formulas can be covered.

Many moms choose to pump and store milk while using formula temporarily, so they can return to breastfeeding later.

Understanding Symptoms: A Quick Comparison Chart

It can help to see how some symptoms compare and overlap. The chart below gives a quick comparison of signs that may show up in cow’s milk protein allergy, dairy intolerance, lactose intolerance, and other food sensitivities. This chart is only a guide—it doesn’t replace your doctor’s advice. If your baby has symptoms that worry you, always reach out to your healthcare provider.

Allergy - Intolerance Chart.jpg

Final Thoughts

It can feel overwhelming when your baby is fussy or spitting up a lot. You’re not imagining things—but it may not be what you think. Many symptoms of allergies and intolerances can look alike, and some are just part of normal baby development. That’s why it’s important to work with your baby’s doctor instead of trying to figure it out alone.

Most breastfed babies don’t need their moms to restrict their diets. But if an allergy or intolerance is suspected, you’re not alone—and you have support!

Making changes can feel overwhelming at first, but with guidance and encouragement, many moms continue to breastfeed successfully.

We're here to help every step of the way!