Is it Allergy, Sensitivity or Intolerance?

Here are a few facts to help you understand what type of reaction you're having

photo of woman holding stomach

Allergies are one of the most common chronic diseases. They occur when your body's immune system sees a substance as harmful and overacts to it. Allergic reactions can range from mild and annoying to sudden and life-threatening. Unfortunately the term "allergy" has become a generic term used to describe allergies, sensitivities and intolerances. To better care for yourself, it's important to know the differences between these responses. Here are a few facts to help you understand what type of reaction you're having and what you might be able to do to improve your quality of life.


You might experience allergies when you come into contact with normally-harmless substances such as tree and grass pollen, mold, dust, animal dander and certain foods. If you have an allergy, your immune system overreacts to an allergen by producing antibodies called Immunoglobulin E (IgE). These antibodies travel to cells that release chemicals, causing an allergic reaction. This reaction usually causes symptoms in the nose, lungs, throat, or on the skin.

In addition to these symptoms, food allergies can also cause gastrointestinal (GI) symptoms such as vomiting, diarrhea and abdominal cramping. Symptoms usually show up within the first two hours of eating the problematic food. Although it is estimated that 6 to 8% of children suffer from food allergies, they usually affect less than 3% of adults.


Intolerance occurs when you don't have the right enzymes to digest certain foods. There is no immune system response to the food, meaning it is not an allergy. When your GI system isn't able to digest foods it causes uncomfortable GI symptoms. An example of this is lactose intolerance. People who are lactose intolerant cannot digest lactose, a type of sugar found in milk and dairy products.

The undigested lactose passes into the large intestine and the bacteria break it down, releasing gas that can cause bloating, pain and diarrhea. Because no immune cells were involved, this is not an allergic reaction.


Unlike intolerance, people with sensitivities do have the appropriate enzymes for digesting whatever food is they are sensitive to. An example of sensitivity is Celiac disease. IgE is not involved, but other immune cells participate. This leads to shrinking of the absorptive surface of the gut which means food cannot be absorbed as well. Eventually, food passes into the large intestine where bacteria break it down.

Food allergies and intolerances are fairly rare and your symptoms could be caused by a number of other factors such as stress, hormonal changes or a different digestive disease. To help relieve your symptoms, your doctor might recommend the use of a food diary and/or an elimination diet to determine what is really triggering your symptoms.