Allergic/Anaphylactic Reaction

An allergic/anaphylactic reaction is a sudden and severe response by the body's immune system to a substance it mistakenly identifies as harmful. This reaction primarily affects the skin, respiratory system, and circulatory system, causing symptoms like hives, swelling, difficulty breathing, and a drop in blood pressure. It occurs when the immune system releases large amounts of chemicals such as histamine, leading to widespread inflammation. These reactions can happen within minutes of exposure to allergens like certain foods, insect stings, or medications. Because it can rapidly worsen, anaphylaxis is considered a medical emergency requiring immediate attention.

Allergic/anaphylactic reaction is an acute, systemic hypersensitivity reaction mediated by IgE antibodies that trigger mast cell and basophil degranulation. This leads to the release of potent mediators such as histamine, prostaglandins, and leukotrienes, causing vasodilation, increased vascular permeability, and smooth muscle contraction. The reaction typically follows exposure to a specific allergen, including foods, insect venom, or drugs, in a sensitized individual. Clinically, it manifests as urticaria, angioedema, bronchospasm, hypotension, and potentially life-threatening anaphylactic shock. Prompt recognition is critical due to the risk of rapid progression to airway obstruction and cardiovascular collapse. The pathophysiology involves a type I hypersensitivity mechanism, distinct from other allergic or non-allergic reactions.