Allergies

Allergies are immune system hypersensitivity to ordinarily harmless substances called allergens. In susceptible individuals exposure can trigger reactions ranging from mild symptoms to anaphylaxis. Most reactions involve IgE antibodies that bind to mast cells and basophils, releasing mediators such as histamine; non-IgE pathways can also occur.

Common allergens include foods (milk, eggs, peanuts, tree nuts, soy, wheat, fish, shellfish), airborne pollens, mold, house dust mites, animal dander, insect venom, latex, and certain medications. Allergies can affect the nose and eyes (rhinitis), lungs (asthma), skin (eczema), or the digestive system.

Diagnosis relies on history and examination, with tests used to confirm sensitization. Skin prick testing and serum specific IgE testing are common; oral food challenges under medical supervision are used to confirm food allergies.

Management emphasizes avoidance of known triggers and preparedness for reactions. Treatments include antihistamines, nasal steroids, and inhaled medications for asthma; epinephrine auto-injectors are essential for anaphylaxis. Immunotherapy options exist for some allergies (pollen, venom) and, in select cases, for certain foods.

Prevention measures and prognosis vary. Some children outgrow allergies (milk, egg, wheat), while others persist (peanuts, tree nuts). Early allergen exposure under professional guidance may reduce risk for some children. Allergies are common worldwide and substantially affect quality of life.