For Patients

Allergies

Allergies are an abnormal and specific reaction of the immune system to harmless substances in the environment called allergens. Allergens can be of various types: pollen, dust, mold, food, occupational substances, mites, insect venom, or animal dander. People with allergies can be exposed to an allergen by breathing it in, swallowing it, or getting it on their skin. After this exposure, a sequence of events occurs that triggers the allergic reaction. The induced production of IgE antibodies (immunoglobulin E) that bind the allergen causes the release of various substances by some cells of the immune system such as mast cells and basophilic granulocytes. The main substance released during allergen exposure is histamine, which causes an excessive reaction of blood vessels and smooth muscle tissue, resulting in the clinical manifestation of the disease. Symptoms may vary depending on the body region affected: on the mucous membranes, the allergy may manifest as asthma or allergic rhinoconjunctivitis ("hay fever"), and on the skin as a rash.

AT-WEB-29-10-2021