What is an allergy?
An allergy is an overreaction of the immune system to certain substances, which are called exogenous, because they come from outside the body. These substances, the allergens, are, for example animal hair, pollen, mould fungi or the excrement of the house-dust-mite.
Normally, the immune system protects the human body from pathogens such as viruses or bacteria. In the case of an allergy, the reaction by the immune system is also called “over-reactive” because the system responds to substances, which are actually harmless to our bodies. According to conservative estimates by the German Allergy and Asthma Association (Deutscher Allergie- und Asthmabund e.V.), around 20,000 substances are known to have allergenic, i.e. allergy-triggering effects. They cause allergic symptoms around the eyes, in the respiratory system, on the skin and in the gastrointestinal tract. Most allergens are protein substances of animal or vegetable origin, for instance from flower pollen, mites or mould fungi.