Allergens are substances unknown to the body having special characteristics.
The reason why some substances have a greater allergenic capacity than others is not well known. It could possibly be due to factors that determine their interaction capabilities with innate immune components (a primitive type of defense).
The vast majority of allergens enter the body through the lungs or the digestive system. Many are present in the air we breath (environmental inhalations) and another large group are food or elements thereof. There are other types of allergens that penetrate the body through bites (poisons). Medication can also be allergenic.
There are allergens that cause a reaction due to direct contact with the skin. These substances (metals, rubber, dyes) are not strictly allergens but cause allergy (contact dermatitis) due to a mechanism that does not involve the IgE antibodies.
1. Environmentally inhaled
These are allergens that are carried in the air and impact the airwave mucosa in the nose and bronchia when we breathe. They account for respiratory allergies (rhinitis, bronchial asthma). The most frequent environmentally inhaled allergens are:
Pollen grains (grass, bushes and trees)
Any food can cause allergy. Food allergies mainly affect the digestive system but can reach the bloodstream and cause general reactions. The most frequent are: