Allergy

An allergy occurs when the immune system overreacts to a normally harmless substance, treating it as a danger. This overreaction can lead to conditions like hay fever, allergic conjunctivitis, allergic asthma, atopic dermatitis, food allergies, and anaphylaxis. Symptoms vary depending on the allergen and can include red eyes, an itchy rash, sneezing, coughing, a runny nose, shortness of breath, or swelling. Common triggers include pollen, certain foods, metals, insect stings, medications, and materials like latex. Both genetic and environmental factors play a role in developing allergies. The immune response involves immunoglobulin E (IgE) antibodies binding to the allergen, then attaching to receptors on mast cells or basophils. This triggers the release of inflammatory chemicals, such as histamine. Diagnosis usually starts with a person’s medical history; skin or blood tests may help in some cases, though a positive test does not always mean a significant allergy exists. Early exposure to potential allergens in childhood might offer some protection. Treatment focuses on avoiding known triggers and using medications like steroids or antihistamines. For severe reactions, injectable adrenaline (epinephrine) is recommended. Allergen immunotherapy, which involves gradually increasing exposure to an allergen, can help with certain allergies, such as hay fever and reactions to insect bites, and FDA-approved oral immunotherapy is now available for food allergies like peanut allergy.