• Parenthood and Pregnancy

How Do I Know If My Baby Has a Food Intolerance?

Published on 11 Mar 2022

How Do I Know If My Baby Has a Food Intolerance?

Feeding a baby can be stressful, especially when you’re worried they might be sensitive to certain foods. Whether your infant is breastfeeding, taking a bottle, or starting to eat from a spoon, it’s common to wonder if something they’re eating could be causing a problem.

Fortunately, food intolerances are rarely serious. But they do happen, and the symptoms they cause might not be what you expect. Keep reading to learn more about what a food intolerance is, how it’s different from a food allergy, and what to do if you think your baby has one. 

What is a food intolerance?

A food intolerance is when a certain food makes you sick or causes a predictable and unpleasant reaction every time you eat it. Food intolerances can take a number of different forms, including: 

  • Digestive problems, like vomiting or diarrhea

  • Skin problems, like a rash or itching

  • Behavioral changes or headaches

What are some common food intolerances in babies?

Babies can experience a variety of reactions to foods they eat. Sometimes these reactions are so mild you can ignore them. For example: 

  • Cabbage, lentils, or beans can result in gassiness and bloating

  • Tomatoes or tomato sauce might cause a diaper rash

But in some children, the reactions cause big enough problems you’ll want to steer clear of a certain food. These are much less common:

How is an intolerance different from a food allergy?

A food allergy is a very specific type of reaction that the immune system causes. When you have a food allergy, your body makes antibodies (often IgE, although some non-IgE-type food allergies also exist) against a certain food or ingredient. Your immune system reacts if you eat that food, resulting in inflammation and allergy symptoms.

How do I know if my baby has a food intolerance?

If your baby has a food intolerance, you’ll notice they have predictable symptoms every time they eat a certain type of food or ingredient.

In general, babies eat a more limited diet than older people do, so discovering a food intolerance is often straightforward. That said, not every reaction, rash, or behavior change a child experiences is due to something they ate. Often it takes time to figure out a connection.

Is my baby lactose intolerant?

Probably not. Cow’s milk is a common cause of food reactions in babies — but the problem doesn’t have anything to do with lactose.

Nearly all babies digest lactose just fine. Lactose is a sugar that occurs naturally in breastmilk, and babies are born with a strong ability to use it for energy. A baby who is born without the ability to digest lactose will have severe medical problems right away.

As we get older, our ability to digest lactose changes. By adulthood, many people (up to 70% of adults in some parts of the world) are lactose intolerant.

One exception is for children who are just recovering from gastroenteritis. These children can develop a temporary lactose intolerance that lasts 1 to 2 weeks. The infection causes damage to the bowel, and it can interfere with the digestion of lactose.

Many people believe their babies are lactose intolerant when the problem is really something different. This doesn’t stop companies from selling expensive lactose-free baby formulas to worried parents, though.

What about cow’s milk protein intolerance?

If your baby is having a reaction to milk (breast or formula), the more likely cause is cow’s milk protein allergy (CMA). Adding to the confusion, this condition is often called “cow’s milk protein intolerance” — even though it’s technically an allergy. It occurs in as many as 7% of babies, and it happens when a baby’s immune system reacts to the proteins in cow’s milk.

Symptoms of cow’s milk protein allergy in babies can include:

  • Fussiness or discomfort after eating

  • Blood in the baby’s poop from inflammation inside the intestines

  • Trouble gaining weight due to inflammation inside the intestines

  • Anemia (low hemoglobin) from bleeding inside the intestines

If you’re nursing, you should be aware that cow’s milk protein could pass into your breastmilk if you drink cow’s milk or if you eat foods made with cow’s milk. Cow’s milk protein is also an ingredient in many baby formulas. For some babies with CMA, even a tiny bit of cow’s milk protein can cause symptoms.

Babies with CMA should be fed in a way that keeps cow’s milk protein out of their diet completely. Fortunately, most babies outgrow this condition early in life. 

Can a food intolerance be dangerous?

Food intolerances don’t generally cause dangerous reactions. In fact, it’s often possible for a person with a food intolerance to eat a small amount of the troublesome food without developing any symptoms at all.

That said, some food allergies and food hypersensitivity syndromes can be dangerous. Sometimes the symptoms of these conditions can overlap with food intolerances, so it’s important to stay in touch with your healthcare provider if your baby or child has severe symptoms.

What should I do if I’m worried my baby has a food intolerance?

If you do start to notice a connection between foods and symptoms, there are a few things you can do.

Eliminate the food for a brief time, then gradually reintroduce it  

If you’re worried your baby is intolerant to carrots, for example, take carrots away for a couple of weeks and see if the symptoms improve. Then offer carrots again, and take note of whether the symptoms come back.

Be careful about eliminating foods that are an important part of your baby’s diet. Cutting out a key food without offering a suitable replacement can cause a nutritional deficiency.

Talk to your healthcare provider 

Your healthcare provider is an important partner when it comes to your baby’s nutrition and feeding. If your baby is experiencing a food reaction, your healthcare provider can work with you to find solutions and help put your mind at ease.

An allergist can help by testing for food allergies

Although there aren’t many specific tests for food intolerances, there are tests for food allergies. Sometimes food allergy testing can help clarify the cause of a reaction your child is having.

Can I test my baby for a food intolerance?

The best way to test for a food intolerance is through trial and error. Does the symptom go away when you eliminate the food? Does it come back when you offer the food again? The answers to these questions will tell you if your child has a food intolerance.

Beware of over-the-counter tests for food intolerances. These tests aren’t regulated, and they don’t tell the full story. Food intolerances show up in ways that a single test simply can’t capture. Plus, these tests can be expensive. If your baby doesn’t show symptoms when they eat a particular food, there’s no reason to test them. 

Can a baby outgrow a food intolerance?

Yes. Food intolerances can change over time. The only way to know if a baby has outgrown a food intolerance is to offer the food again and see what happens. 

The bottom line

Food intolerances don’t happen very often in babies, but they do show up occasionally. If you’re concerned your baby might have a food intolerance, try stopping the food and watching what happens. If the food you’re worried about is an important part of your baby’s diet, talk to your healthcare provider about alternative ways to make sure your baby gets the nutrition they need.


Connors, L., et al. (2018). Non-IgE-mediated food hypersensitivity. Allergy, Asthma, and Clinical Immunology: Official Journal of the Canadian Society of Allergy and Clinical Immunology.

Heine, R. G., et al. (2017). Lactose intolerance and gastrointestinal cow’s milk allergy in infants and children – Common misconceptions revisited. The World Allergy Organization Journal.

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