Anaphylactic shock is caused by a severe allergic reaction in which the body's immune system overreacts to a normally harmless substance called an allergen. This overreaction triggers the immune system to release a flood of chemicals, such as histamine and other inflammatory mediators, which cause widespread effects including sudden blood vessel dilation, a drop in blood pressure, and narrowing of the airways. These changes can rapidly lead to shock and difficulty breathing, making anaphylaxis life-threatening if not treated promptly

. Common triggers of anaphylactic shock include:

• Foods, especially peanuts, tree nuts, shellfish, fish, milk, eggs, wheat, soy, and sesame. Food allergies are the most frequent cause in children and young adults

• Insect stings from bees, wasps, hornets, yellow jackets, and fire ants

• Medications such as antibiotics (penicillin), aspirin and other NSAIDs, muscle relaxants used in anesthesia, and intravenous contrast dyes used in medical imaging

• Latex exposure

• Less common triggers include physical factors like exercise or temperature changes, food additives, and some vaccines

The underlying mechanism involves immunoglobulin E (IgE) antibodies binding to the allergen, which activates mast cells and basophils to release mediators like histamine, prostaglandins, leukotrienes, and platelet-activating factor. These mediators cause the symptoms of anaphylaxis including vasodilation, increased vascular permeability, bronchoconstriction, and heart muscle depression

. In summary, anaphylactic shock results from a rapid, severe allergic reaction to allergens such as certain foods, insect stings, medications, or latex, leading to systemic release of inflammatory chemicals that cause life- threatening cardiovascular and respiratory symptoms