What’s the Difference Between a Food Allergy and Food Intolerance?

Food intolerances, allergies, and food sensitivities are common among people of all ages. In 2012 alone, 4.1 million children reported food allergies. When we eat something our body does not agree with, we can often tell immediately. We may experience itching, nausea, sneezing, rashes, diarrhea and other symptoms.  

The terms “allergy,” “intolerance,” and “sensitivity” are often used interchangeably. However, there are important differences between the three, especially if you’re concerned about if your baby may have an allergy. Let’s explore them in more detail. 

Food Allergies 

Food-related allergies have the most severe reactions of the three. This occurs when the immune system thinks of a certain food as an attacker. Allergic reactions can be as minor as a rash or as severe as swelling and anaphylactic shock. 

Food allergies can develop at any time in a person’s life, but are most likely to occur at an early age. If you have a history of food allergies in your family, there’s a higher chance your baby may have one too.   

The fundamental difference between allergies and intolerance is that food allergies involve the immune system whereas food intolerances do not. Therefore, food intolerances rarely ever have life-threatening consequences. However, an accidental exposure can cause anaphylaxis and/or life-threatening consequences for those suffering from a food allergy.

Food allergies can be hereditary, have an increased likelihood of developing if you baby has eczema, and may also be brought on by environmental factors. In contrast, intolerance can be random, or it can be brought on by over-exposure to a certain food that the body can’t digest (lactose intolerance for example).

Parents of babies with known allergies must be much more prepared when eating at restaurants or at others’ homes than those without allergies. While reactions to food intolerances may be uncomfortable and distressing, they are unlikely to be inherently life-threatening.

What causes a food allergy? 

We may develop a food allergy after being exposed to a protein our body thinks is harmful. The first time we consume food that contains that protein, our immune system responds by creating antibodies to defend ourselves. When we eat that food again, our body releases the same antibodies and other chemicals, including histamine, to fight the perceived threat. 

The allergy symptoms we experience generally depend on where in our body the histamine is released. If our body releases it in the throat, ears and nose, we may experience itching, swelling, and even trouble breathing. Similarly, we may develop hives or a rash if histamine is released in our skin. These are all things to be on the lookout for with your baby. 

What are the symptoms of a food allergy? 

Allergy symptoms are typically the most severe. Symptoms include:

  • Wheezing
  • shortness of breath
  • low blood pressure
  • face, mouth or throat swelling
  • itching
  • red hives
  • abdominal pain
  • nausea
  • diarrhea 

These symptoms may worsen rapidly, so it is important to act quickly in such a situation. Initial symptoms of anaphylaxis reflect those listed above and should be treated immediately. An allergy can even affect the organs if left untreated. 

Parents of babies with severe allergies usually carry an epinephrine shot device or an EpiPen. In particularly difficult cases, these pens can save a baby from anaphylaxis.

Are some foods more likely to cause allergic reactions than others?

Yes – eight foods are responsible for 90 percent of all food-allergic reactions

Many people eventually grow out of milk, egg, soy and wheat allergies. Peanut and shellfish allergies generally last longer and impose more severe symptoms. Other less common food allergens include sesame seeds and celery. 

Because this list is relatively short, it is usually easy to discover which food(s) your baby is allergic to. Allergies can be passed through families, so consider allergies you have or ask your parents about possible allergies if you suspect your baby has one.  

If you suspect your baby may have an allergy, monitor what they’re eating and the food they’re coming into contact with directly through eating, or being in the same room with. (This is important for foods like peanuts and shellfish, which can cause more serious symptoms.) 

Once an allergy is discovered, it’s a good idea to avoid all similar foods. For example, if your baby is allergic to shrimp, they will also likely react to other shellfish, such as crab. If your baby is allergic to nuts, it’s a good idea to avoid dates and stone fruits. This is called cross-reactivity. 

While avoiding so many foods can make eating on the go difficult, it is the best way to ensure your baby doesn’t have unexpected reactions. If your baby experiences severe symptoms, such as swelling, talk to your doctor about whether you need to carry an EpiPen. 

How quickly does a food allergy show? Is there any way to remedy a food allergy? 

Food allergies can be brought on by even tiny amounts of that food. As a result, the only viable way to avoid reactions is to avoid the foods that trigger them. Unfortunately, some people are extremely allergic to things like peanuts. That said, introducing your baby to allergens as early as 4 months of age can reduce allergies by 80 percent.

Food Intolerance 

Food intolerance occurs when the body is not able to break down and digest certain foods.  Although an uncomfortable experience, it’s manageable and non-life threatening. The most common type of food intolerance is lactose intolerance, which affects approximately 10 percent of Americans

Lactose intolerance occurs when our gut doesn’t produce enough of the enzyme lactase to process the lactose. A parent can pass on lactose intolerance to their baby, or it can happen as we age and produce less lactase. Research shows that only about one in three people can digest lactose beyond eight years old.

Causes of food intolerance can include:

  • Irritable bowel syndrome (IBS)
  • Sensitivity to additives in food, such as sulfites
  • Psychological factors, such as recurring stress associated with certain foods
  • Celiac disease – this disease shows features of a true allergy because it affects the immune system. While a celiac episode may trigger uncomfortable symptoms (such as stomach ache, headaches, and joint pain), those with celiac disease are not at risk of going into anaphylactic shock. 

Your baby is less likely to have lactose intolerance, but it’s certainly something to be aware of.

How quickly does a food intolerance show? 

In comparison, food intolerances are usually dose-related. In other words, those with a specific food intolerance may not experience noticeable symptoms unless they eat a large amount of the food or eat small amounts frequently. For example, a baby with lactose intolerance may be able to eat a cheese sandwich every so often, but they may become unwell if they drink a large glass of milk. 

Do I have to avoid giving my baby certain foods if they’re intolerant? 

Being intolerant to a food means your baby is going to be uncomfortable if they consume that food, but eating that food every so often won’t often result in much more than a bad tummy. If your baby loves dairy products, then eating a little bit of cheese or having a little yogurt every so often might be a trade-off you’re willing to make to keep them happy and on a balanced-diet. If they react strongly, look elsewhere for the same dietary benefits.

Food Sensitivity 

You may be wondering what the difference is between a food intolerance and a food sensitivity. Contrary to popular belief, there are clear differences.

Harvard Medical School explains that after eating certain foods, a large part of the population experiences symptoms that are not related to food intolerances, food allergies, or celiac disease. Like an allergic reaction, a food sensitivity is thought to be caused by an immune reaction. Unlike an allergy, however, this may be a temporary problem that can go away later in life. It can be outgrown and potentially eliminated with reintroduction to the food at a later time.

 A food sensitivity is also different from an intolerance due to how the body responds–food intolerances stem from the body’s inability to break down certain foods, then rejecting them. Someone with a food sensitivity will have a response more similar to an allergic reaction.

Symptoms of food sensitivity often include stomach pain, rashes and joint pain. These symptoms are not life-threatening but can cause long-term problems if ignored. If your baby has a sensitivity, they may be uncomfortable after meals and come out in a rash. 

Given the fact that this manifests in ways similar to allergies, it’s best to consult with your baby’s pediatrician to determine the best way to approach food sensitivity.

How can you tell the difference between an allergy, an intolerance, and a sensitivity? 

A person’s physical reaction is the most accurate way to identify which they have, it’s also the easiest way to tell if your baby has a food-related issue. 

When identifying your baby’s food allergy, you may want to ask yourself the following questions:

  • How much did my baby eat before reacting to the food? This could help to differentiate between an intolerance and an allergy. 
  • Did the reaction come on suddenly or within an hour of your baby eating the food?
  • Did anyone else react to the food? This can help to rule out food poisoning if your baby ate the same food as others.
  • How was the food prepared? Again, this can determine if your baby is reacting to food poisoning.
  • Does your baby always react this way when they eat this specific food or is it the first time they’ve experienced this?
  • Did your baby have any symptoms that were not related to their stomach? Food intolerances usually take the form of nausea, stomach bloating, wind and diarrhea. 

These questions can all be useful in figuring out the best course of action to take. If you have any doubt and believe your baby is having a severe allergic reaction, go to the emergency room. 

Your pediatrician may recommend an elimination diet if symptoms are frequent and mild.  For this reason, it’s also best to only introduce your baby to one new food at a time so that you can pinpoint what causes changes. There are also allergy tests available if your pediatrician believes that your baby has food allergies.

Key Takeaways for Parents

Parents are better equipped to deal with food allergies and intolerances than ever before. Now, your baby with allergies can remain safe, happy, and healthy.


All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease. 

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