In an allergy, the body has a hypersensitive reaction to substances that are harmless in themselves, such as proteins of pollen. The incidence of allergies in industrialised countries is partly linked to our modern lifestyle.

Hypersensitivity reaction of the body

An allergy or an allergic disease means a hypersensitivity reaction of the body to harmless foreign substances. These substances, nearly always proteins (e.g. of pollen, house dust mites, animals, foods or medicines), are referred to as allergens. If sufferers come into contact with these allergens, for instance through their diet or by inhaling them, the body reacts with a defence that is inappropriate and is referred to as an allergy. This reaction to the foreign-body substance leads to a variety of allergic symptoms.

Around 35 per cent of the Swiss population are sensitised to allergens and hence have a predisposition to allergies. Approximately 20 to 25 per cent have already displayed allergic symptoms. These figures are in line with experiences in other industrialised countries. The risk of allergy is unequally distributed. Children whose parents or siblings already suffer from allergies have a higher risk of developing allergic reactions as well.

In recent years and decades, allergies have generally increased sharply. The reasons for this have still not been fully explained. It is obvious, however, that allergies are on the increase in countries with a high standard of living and improved hygiene. There is an assumption that the high hygiene standards are partly responsible. The immune system is put under far less stress from natural enemies (but also harmless bacteria, viruses), so that it has forgotten how to distinguish between harmful and harmless substances and overreacts to harmless proteins.

Editors: aha! Swiss Allergy Centre in co-operation with the Scientific Advisory Board. For prevalence figures, see source references.