Difference between Food Allergy and Food Intolerance

Key Difference:  Food allergy is an immune response due to misjudgment of harmless food. On the other hand, food intolerance is a chemical reaction in which a body is unable to digest some types of food.

Food Allergy and food intolerance are two differ things, and therefore must not be confused due to similar signs and symptoms. Food allergy and food intolerance are caused by different reasons.

Food Allergy occurs when the immune system of the body wrongly considers a consumed item as threatening to the body. In its protective mode, it fights the food protein and this response affects the gastrointestinal tract, skin, respiratory system, etc. This overreaction of the immune system starts depicting its symptoms within seconds or hours after eating that particular food.

Generally, allergic reactions are not very dangerous. However, a severe allergic reaction can be life threatening too. Therefore, it is important to seek medical advice in the case of a food allergy. Some common food allergies are caused due to fish, peanuts and treenuts.

Food intolerance shares some symptoms with allergy, and therefore many times are considered to be the same. Food intolerance is totally different from food allergy, as it has no connection with the functioning of the immune system. It takes place due to the inefficiency of the digestive system to digest some proteins. A body’s inability to digest a food is termed as intolerance.

A common example of food intolerance is lactose intolerance in which people are unable to digest lactose which is a sugar found in milk and dairy.

Food allergy and food intolerance, both share some of the symptoms like nausea, vomiting, diarrhea and nausea.  However, in the case of allergy some of the symptoms may include – rash, itchy skin, shortness of breath, chest pain and sudden drop in blood pressure. On the other hand, Food allergy may include symptoms like heartburn, headaches, irritation, nervousness, gas, cramps or bloating.

Food allergy and intolerance should only be diagnosed and treated medically. They both are covered under the food sensitivities.  Food allergy has obvious types of symptoms whereas intolerance has subtle symptoms. A small portion of food is also capable of triggering an allergic reaction, whereas intolerance is not predominantly affected by quantity of the food. Allergies are generally non reversible, whereas intolerance is reversible. The best way of treatment is to toatally avoid food which can cause an allergy or intolerance.

Comparison between Food Allergy and Food Intolerance:


Food Allergy

Food Intolerance


It is an immune response due to misjudgment of food

It is a chemical reaction in which a body is unable to digest some types of food.


  • Rash, hives, or itchy skin
  • Shortness of breath
  • Chest pain
  • Sudden drop in blood pressure        
  • Gas, cramps, or bloating
  • Heartburn
  • Headaches
  • Irritability or nervousness

Common Cause

Generally peanut and nut

Milk (lactose intolerance) and gluten

Portion size

These are often hereditary

It is generally not dependent on the portion size

It is often related to the portion size

Occurrence of symptoms

Generally immediate

Generally gradually

Life Threatening

Can be

Is generally not

Frequency of symptoms

Every time food is eaten

May or may not happen every time food is eaten


Prick or RASR

Electro-dermal screening or Blood Immunoglobulin G

Image Courtesy: seedtofeedme.blogspot.com, almondjay.com

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