Classification of allergies | Food allergy – symptoms, allergens and therapy

Classification of allergies

Allergies in general are divided into 4 types of allergies. They differ in the way the allergy develops at the molecular level. Externally they differ in the duration between allergen contact and the first occurrence of symptoms.

Type I is the allergy of the immediate type. The symptoms appear after seconds to minutes. Type II is called the cytotoxic type.

Symptoms appear after about 6-12 hours. Type III allergy involves the formation of immune complexes. Symptoms also occur after 6-12 hours.

Type IV describes an allergy of the delayed type. Symptoms appear after 12-72 hours. An example of a type IV allergy is a drug exanthema, a rash that can develop after contact with a drug.

However, there are also rashes after taking medication which appear after only a few minutes, i.e. they belong to type I allergies. Like type II and III allergies, type IV allergies are rather rare, type I allergies are by far the most common. Food allergies also belong to type I. Other Type I allergies are hay fever and allergic asthma.