Bigger Kids

How to know if your kid has a food allergy or food intolerance

Frequent stomach discomfort could be a sign of a food allergy or intolerance. Here are some symptoms to watch out for.

By Susan Spicer
FoodSensitivities-1 Photo: iStockphoto

Around the time he turned one, Amanda Philip’s son, Rush, started having stomach aches at night. “He’d cry, grimace, grab his tummy, tuck up his legs, then straighten them out. He was in obvious pain,” says Philip.

You’re probably introducing your toddler to a whole range of new foods. But what if, as happened with Philip, you begin to suspect that something your child is eating is causing him discomfort? As Philip found, nailing down the culprit is not always easy: “Because it wasn’t an everyday occurrence, it was hard to pinpoint the cause of Rush’s stomach aches.”

Food allergies and intolerances are quite common in toddlers, says Robert Issenman, a paediatric gastroenterologist at McMaster Children’s Hospital in Hamilton and past president of the Canadian Paediatric Society.

True allergy is a reaction of the body’s immune system to a protein in foods, such as wheat, milk, eggs, soy or peanuts. The symptoms are most often wheezing or other respiratory symptoms, hives or vomiting. Ingestion, touch or, in a person with really severe allergy, inhalation can trigger a reaction. Food allergy in children is more common when there’s a family history of eczema, allergy, asthma or hay fever, says Issenman.

Food intolerance is difficulty digesting the sugar in a food and symptoms are usually digestive — gas, bloating, diarrhea and stomach cramps, though some parents report rashes associated with food intolerance. “It’s important for parents to know that a food intolerance is uncomfortable, but it’s not dangerous,” says Issenman.

Lactose intolerance is the most common, and occurs when people don’t have the enzyme required to digest lactose, the sugar in milk. “There’s a genetic link here; lactose intolerance is actually the norm for people who come from areas of the world where cow’s milk wasn’t traditionally a part of the regular diet (Asia and Africa, for example).” Quite often, says Issenman, children who start out able to digest milk will actually develop an intolerance for cow’s milk between the ages of three and five.


Celiac disease is a reaction of the bowel to gluten, the protein found in such foods as wheat, rye, barley and oats. “Yes, we do see toddlers with it,” says Issenman, “It’s really bad for you because the gluten damages the lining of the intestine. It’s much more common in Irish, Indo-European, Italian, English and Scandinavian people.

A correct diagnosis and treatment of celiac “is one of the most miraculous things in medicine,” says Issenman. “A two-year-old with it looks very ill — small and malnourished. They make a complete recovery on a gluten-free diet.”

Fructose intolerance is an inability to handle cane or fruit sugar; those with the intolerance will have digestive symptoms. “Humans were not designed,” says Issenman, “to consume the amount of sugar in several apples in a few minutes — which is what they’re doing when they drink apple juice. If children drink juice from morning to night, they’re likely to have belly pain and diarrhea.”

If you suspect your child has a food sensitivity, the first step is to see your child’s doctor, says Issenman. But parents should do some homework. Identify food your child has consistently consumed when symptoms occurred, and also foods he consumes in large quantities.

Philip was able to put two and two together when Rush had a stomach ache during an afternoon nap. “He had been munching on frozen corn kernels earlier. Up until that point, I really had no idea what was affecting him,” she says. (Issenman says intolerance to corn is fairly common because it’s one of the hardest things to digest.)


Issenman cautions parents against eliminating foods from a child’s diet without discussing it with their doctor first. “Some of the most severe cases of malnutrition we see are caused by well-intentioned parents who have put their children on overly restrictive diets.” At this age, kids are growing quickly and they need to eat a wide range of nutritious foods.

If you’re seeing very dramatic reactions, for example, hives or breathing difficulties (usually to peanuts), “special consideration is required because even a very small amount can be life-threatening,” says Issenman.

So how is a diagnosis made? The doctor will do a physical examination and take a history. The doctor will then determine whether it’s an allergy or an intolerance. For instance, if a child seems to have a problem with milk and symptoms persist even if the child has lactose-free milk, it’s most likely a milk allergy.

If symptoms suggest a food intolerance, but you and your doctor aren’t able to figure out what it is, Issenman says, the first step is often a lactose-free diet.

Celiac disease is diagnosed with blood screening and a biopsy.


Skin prick tests are sometimes used to pinpoint food allergies. “It’s not pleasant for little kids, so we test for the four or five most likely allergies,” says Issenman.

At 2½, Rush is now able to enjoy corn on the cob with the rest of the family without ill effects. “There’s excellent research to show that very often children outgrow early food sensitivities. The exceptions are celiac disease and peanut allergy, which, more often, are lifelong.

Read more: How my son overcame his peanut allergy> What to do when your picky eater goes on a food jag> When to stop feeding your baby lactose>

This article was originally published on Jan 03, 2016

Weekly Newsletter

Keep up with your baby's development, get the latest parenting content and receive special offers from our partners

I understand that I may withdraw my consent at any time.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.