If you have a reaction every time you eat a certain food, you may believe you have a food allergy. Food allergies are caused when the body’s immune system responds to a food as though it was a threat. You can read more about how food allergies happen in the food allergy overview.
Where symptoms occur
It is important to know that not every reaction to food is caused by a food allergy. Food allergies can cause a reaction anywhere in the body because allergen antibodies travel through the blood stream. So food allergies can cause hives, sinus problems, and stomach discomfort. Food intolerance is more likely to cause a reaction in the digestive tract – the stomach or intestines. Food intolerance can sometimes cause as strong a reaction to food as a food allergy. Food intolerance may cause symptoms soon after a food is eaten or symptoms may be delayed for several days. Food allergy symptoms often appear as soon as the food is eaten. The most severe food allergy reactions may cause anaphylaxis which is a swelling of the airway and sudden drop in blood pressure that can very quickly be deadly.
Symptoms over time
Because of the rapid onset of symptoms, food allergies are most often diagnosed in children, although some cases are not diagnosed until adulthood. Food allergies typically remain the same over time, while food intolerances can build up over time and become gradually worse. In some cases, a particularly stressful event may seem to trigger the onset or sudden worsening of food intolerance symptoms.
Immune system involvement
The most significant difference between food allergy and food intolerance is that the immune system is not involved in intolerance. Food intolerance is often caused by something that is lacking in the body’s digestive system that limits the ability to digest certain foods. For example, someone with lactose intolerance does not have the enzyme necessary to digest dairy foods.