Illustration of allergic reactions in the skin (eczema) and the nasal mucous membrane as a result of contact with allergens such as mold, pollen, haptens, dust mites, hairs. On the left, an illustration of healthy skin coming into contact with allergens (on the left) and the reaction that follows infection (on the right) : dilation of blood vessels and the immune reaction of macrophages and lymphocytes that migrate to the inflammation, followed by the epidermis swelling (oedema) and shedding of the upper epithelial cells. Illustration of a healthy nasal mucous membrane coming into contact with allergens (on the left) and the reaction that follows infection (on the right) : overproduction of mucus (yellow), destruction of the mucous membrane epithelial, dilation of blood vessels, immune reaction in the macrophages and lymphocytes (pink cells in the blood vessel) as a result of inflammation (red area).