Food Intolerance vs. Food Allergy


photo of Healthy girl drinking milk from glass in the kitchen

It’s important to know the difference between a food intolerance and a food allergy, as each is managed differently.

What is food intolerance?

A food intolerance involves the digestive system. Due to an enzyme deficiency or chemicals in the food, the meal is not “broken down” correctly in the body and causes stomach distress.

Discomfort comes on gradually and may include:

  • nausea
  • stomach pain
  • diarrhea
  • vomiting
  • cramping
  • headache
  • heartburn

You may also just feel short-tempered.

With a food intolerance, you may be able to eat small amounts of the food but have problems when you eat a lot of the food.

What foods cause food intolerance?

The most common food intolerance is to lactose intolerance. Lactose is a sugar found in milk and other dairy products.

Some people are intolerant of sulfites or food additives.

What is a food allergy?

A food allergy impacts the immune system and can be very serious. Your body recognizes the food as an “intruder” and mounts an “attack” to defend itself: the immune system overreacts and releases IgE antibodies.

The allergic reaction usually comes on very quickly, and while symptoms can be mild, they can also quickly turn life-threatening.

Symptoms of a severe allergic reaction (anaphylaxis) usually involve more than one body organ

  • hives
  • skin rash
  • swelling, often around the mouth, on the tongue or in the throat
  • shortness of breath
  • coughing
  • wheezing
  • nausea
  • stomach pain
  • diarrhea
  • vomiting
  • weak pulse
  • dizziness.

What foods cause a food allergy?

Nine food categories cause 90 percent of the allergic reactions to foods:

  • peanuts
  • tree nuts
  • fish
  • shellfish
  • eggs
  • cow’s milk
  • soy
  • wheat
  • sesame

What is the difference between food intolerance vs. food allergy?

This chart explains the ways food intolerance and food allergy are different:

Food IntoleranceFood Allergy
Where reaction takes placeDigestive systemImmune System
Intensity of reactionMild to moderate discomfortCan be life-threatening
SymptomsGastrointestinalMultiple body systems; skin, respiratory, heart, and gastrointestinal
Reaction timeMay be delayedUsually immediate (within 30-60 minutes)
Action to takeSee healthcare provider

Call 911

How is food intolerance treated?

People with food intolerance can feel very uncomfortable and should see their healthcare provider for guidance. There are some medications and digestive enzymes that can help.

How is food allergy treated?

If it’s a food allergy, it’s important to avoid the food that causes the allergy – and always carry epinephrine auto-injectors in case of an accidental exposure. If you or your child show signs of a life-threatening allergic reaction, use epinephrine and then call 911 to go to the emergency department.