Alerg

Alerg, or allergy, is an exaggerated immune response to substances that are typically harmless to most people. The majority of allergic reactions are mediated by immunoglobulin E (IgE) antibodies and involve type I hypersensitivity. Not all reactions are IgE-mediated; some are delayed or non-IgE.

Common allergens include pollen, mold spores, dust mites, animal dander, certain foods (peanuts, tree nuts, milk, eggs, wheat, soy, shellfish), insect stings, medications, and latex.

Symptoms vary by organ system and can range from mild to life-threatening. Nasal itching, sneezing and runny nose, itchy eyes; skin reactions such as hives or eczema; respiratory symptoms including wheeze and throat swelling; in severe cases anaphylaxis.

Diagnosis relies on clinical history and tests. Skin prick testing or serum specific IgE testing can identify sensitization. Oral food challenges under medical supervision may be used for suspected food allergies.

Management focuses on avoidance of known triggers and treating symptoms. Antihistamines, intranasal corticosteroids, and leukotriene receptor antagonists address nasal and allergic symptoms; inhaled corticosteroids for asthma; epinephrine auto-injectors for anaphylaxis. Allergen immunotherapy (subcutaneous or sublingual) can reduce sensitivity for certain allergens and may alter the disease course in some individuals.

Epidemiology: allergies are common worldwide, affecting a substantial proportion of children and adults, with prevalence varying by region and age. With appropriate management, most people can live active lives, though some allergies persist lifelong.