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In your baby’s first year of life, you’re figuring out what makes them tick – and what doesn’t. These early months and years are when kids are likely to show signs they have a food allergy or intolerance, because their immune and digestive systems are still developing. 

Although both cause health issues for your baby, a food allergy and a food intolerance aren’t the same thing. It’s important to know the difference so you know how to approach feeding your baby.

Food Intolerance

An intolerance to a food affects the digestive system. It means your baby has trouble digesting a certain food or food group. Your baby might have a food intolerance if their body doesn’t have any or enough of a certain enzyme to digest a food fully. 

Examples include:

  • Lactose intolerance, which means they have a hard time digesting dairy products
  • Gluten intolerance, which causes discomfort after foods with wheat, rye, or barley
  • Fructose intolerance, which makes it hard to fully absorb sugar in fruits and vegetables

A food intolerance reaction usually doesn’t happen right away. The symptoms are uncomfortable, but they aren’t life-threatening. 

Typically, a food intolerance causes:

  • Diarrhea
  • Tummy pain
  • Mild skin rashes and itching
  • Gas
  • Bloating

Testing for Food Intolerance

Your pediatrician will want to rule out a food allergy before testing for food intolerance to be sure it’s not more serious. They may refer you to a GI specialist or nutritionist to help pinpoint what’s causing a reaction. 

A helpful tool for discovering what’s causing an intolerance is a food diary. You’ll record everything your child eats (and/or everything you eat, if you are breastfeeding your child) along with any symptoms that show up. As you identify potential triggers, you can start to eliminate those foods and see if the symptoms get better. 

You can’t treat a food intolerance, but you can help ease some symptoms. Ask your pediatrician about trying over-the-counter lactase enzyme drops that can help relieve discomfort from lactose intolerance. 

Food Allergy

When your child is allergic to a food or food group, their immune system treats the food as a foreign invader. Your baby’s body makes antibodies for that food. The next time that food enters your baby’s system, the immune system releases these antibodies along with a chemical called histamine. 

Once histamine is in your child’s body, within minutes to hours, they can have some or many of the following reactions:

  • Vomiting
  • Diarrhea
  • Cramps

As well as serious, sometimes life-threatening symptoms, including: 

  • Hives
  • Swelling
  • Eczema
  • Itching or swelling of the lips, tongue, or mouth
  • Itching or tightness in the throat
  • A hard time breathing
  • Wheezing
  • Lowered blood pressure

These symptoms are called anaphylaxis and require medical attention right away with a shot of epinephrine (EpiPen) and a follow-up trip to an emergency room. If anaphylaxis isn't treated right away, it can be fatal.

The most common food allergens include:

  • Peanuts
  • Tree nuts
  • Eggs
  • Shellfish
  • Fish
  • Milk
  • Soy
  • Wheat

Some babies can outgrow their food allergies, but it depends on which allergens affect them. It’s more common for kids to outgrow allergies to cow’s milk, egg, soy, and wheat. They’re less likely to grow out of an allergy to peanuts, tree nuts, fish, and shellfish.

Testing for Food Allergies

Your baby’s pediatrician will review your baby’s symptoms and history with you before testing. Then your baby may need a blood test and/or a skin prick test to see if their body is producing antibodies for certain foods.

  • Blood test. A doctor, nurse, or technician will draw a vial of blood from your baby using a syringe and send it off to a lab to test for the antibodies.
  • Skin prick test. Your doctor will use a tiny, sharp surgical instrument filled with a small amount of the allergen to prick your child’s skin. If a bump shows up in 15-30 minutes, that’s a sign your child likely has an allergy.

Things to Think About While Breastfeeding

Breast milk doesn’t typically cause an allergic reaction for breastfeeding infants. If your breastfed baby is having an allergic reaction, it’s most likely due to the cow’s milk in their mother’s diet. This happens in about two to three out of every 100 exclusively breastfed babies.

Signs of a dairy allergy include: 

  • Severe colic
  • Tummy discomfort
  • Skin rash (such as eczema or hives)
  • Vomiting
  • Severe diarrhea, sometimes with blood
  • Trouble breathing after breastfeeding

If you notice any of these symptoms, call your pediatrician right away. 

Breastfed babies may show discomfort after nursing if their mother’s diet has spicy foods that cause gas, such as fiber-filled foods. This isn’t an allergy or intolerance. Mothers can temporarily avoid these foods to see if it stops the problem. If it doesn’t, talk to your doctor about whether your baby might have colic. 

Figuring Out Formula

Formula-fed infants can show symptoms of intolerance or allergy to milk or soy in formula. Ask your pediatrician for guidance on which formula is best. 

Most formula-fed infants who are allergic or intolerant to dairy can tolerate formula labeled “hypoallergenic.” There are three kinds:

  • Partially hydrolyzed. This formula is made with cow’s milk proteins that are already broken down into small pieces, making them easier to digest. This option isn’t for babies with a milk allergy because the proteins are not small enough to prevent a reaction. This can be a good option for babies who are lactose intolerant.
  • Extensively hydrolyzed. The process for this formula involves breaking down the milk protein even smaller than it is in partially hydrolyzed formula. Babies with milk allergies can try this option. 
  • Amino acid-based. This formula option contains only milk proteins broken down completely into their amino acid form. This gives babies all the nutrition they need without triggering their immune system. 

Show Sources

Photo Credit: Kenishirotie / Getty Images


Children’s Hospital of Philadelphia: “Food Intolerance.”

National Childhood Trust: “Food intolerances in babies.”

UCSF Benioff Children’s Hospitals: “Managing Food Allergies.”

Johns Hopkins Health: “Food Allergies in Children.”

Mayo Clinic: “Anaphylaxis.”

Canadian Paediatric Society: “Food allergy vs. food intolerance: What is the difference and can I prevent them?”

Allergy & Asthma Network: “Ask the Allergist: Outgrowing a Food Allergy.”

Children’s Health: “Pediatric Food Allergy.”

American Academy of Pediatrics: “Infant Allergies and Food Sensitivities.”

Prevent Food Allergies: “Does My Baby Need Hypoallergenic Formula?”