A severe allergic reaction, also known as anaphylaxis, is a rapid and potentially life-threatening response to an allergen. Common triggers include certain foods, insect stings, medications, and latex. Symptoms can develop quickly and may include difficulty breathing, swelling of the throat, hives, and a rapid drop in blood pressure. Immediate treatment is crucial for anaphylaxis. The first line of defense is usually an injection of epinephrine, which can help reverse symptoms. Individuals with known severe allergies are often advised to carry an epinephrine auto-injector and to seek emergency medical help if they experience symptoms of a severe allergic reaction.