A reaction to a substance called an “allergen, that generates a particular type of immune response.”. Examples of allergens are dust mites, mould, tree weed and grass pollen, as well as food allergens such as milk, egg, soy, wheat, nut or fish proteins. Allergy starts with sneezing and a runny nose (rhinitis), red and itchy skin (“eczema”) or, in severe cases, even life-threatening reactions (anaphylactic shock).
