Allergy (from Greek — reaction to the unknown) is elevated sensitivity to specific substances — allergens — present in the body or the environment. Over the last 20 years, the prevalence of allergies has doubled. This is linked to multiple factors: deteriorating ecological situation, changed lifestyle and dietary habits, emergence of new allergens, stress, and working environment, among others.
Allergy is not an illness, but rather a group of various illnesses based on a common pathological process. The immune system plays the key role in the origination of an allergic reaction. It is the immune system that protects the body from harmful and alien elements. The way the immune system operates is very complex; it is based on producing antibodies in the blood of humans or animals to neutralise harmful elements.
In case of allergies, the guard of the organism — the immune system — clearly oversteps the permissible self-defence boundaries. The immune system perceives the least harmful substances as harmful for the body, and the immunity starts self-defence by keenly reacting to any substance. It is this aggressive reaction by the immune system on external environmental factors (hypersensitivity) that is an allergy, whereas antigens, which trigger this inadequate reaction of the body, are called allergens.