About food intolerance

A food intolerance is a reaction to the food you’re eating. The reaction might be because your body can’t properly break down the food. Or it might be because your body is irritated by a chemical that’s found in the food.

Some people can cope with small amounts of foods they’re intolerant of.

Food intolerances aren’t the same as food allergies. Food allergies happen when your immune system reacts to a food you’ve eaten. Food intolerances don’t involve your immune system. Food allergies are generally more severe and have more symptoms than food intolerances.

Symptoms of food intolerance

Symptoms of food intolerance include:

Food intolerance symptoms are often delayed and can appear up to two days after you have the food you’re intolerant of.

Food intolerances don’t cause anaphylaxis symptoms like breathing difficulties and mouth swelling.

If you think your child has food intolerance or you’re not sure why your child is having symptoms, it’s best to talk with your GP.

Common food intolerances

The most common food intolerances are to:

  • lactose, which is the sugar in dairy products
  • wheat
  • food additives, including flavour enhancers like MSG
  • fructose, which is the sugar in fruit.

Diagnosing food intolerance

Elimination diets are the most common test for food intolerance. This involves removing from your child’s diet foods that might cause intolerance. Then you reintroduce the foods one at a time to work out which food is causing the intolerance.

For suspected fructose or lactose intolerance, doctors might also use a breath test. This tests the amount of hydrogen gas in the child’s breath. Lactose-intolerant children will have higher levels of hydrogen in their breath.

Diagnosing lactose intolerance can sometimes be tricky because symptoms can look similar to food allergy.

What to do about food intolerance

If a doctor has diagnosed food intolerance in your child and your child eats something you know he’s intolerant of, the symptoms will usually clear up by themselves. Your child shouldn’t need urgent medical attention.

If your child’s symptoms include diarrhoea, you need to make sure he gets plenty of water.

How long do food intolerances last?

We don’t know much about how likely children are to grow out of food intolerances. How long a food intolerance lasts depends on the food and the reason your child’s body is reacting to it.

If you think your child has grown out of a food intolerance, it’s best to speak with your GP or dietitian. They might suggest you carefully introduce the food into your child’s diet at home to check whether the food intolerance has gone.