Anaphylaxis is an immediate allergic reaction occurring after exposure to an inciting agent. Reaction is rapid, dramatic and may not be anticipated. Death can occur due to vascular collapse (drop in blood pressure), severe asthmatic reaction or airway obstruction.
Anaphylaxis can occur after exposure (either by ingestion or injection) to a compound. Included are common allergens such as foods (peanut, nut, shellfish), drugs (penicillin or other antibiotics), stinging insects such as bees or fire ant, latex (rubber), contrast media used in X-rays and allergy shots. Occasionally anaphylaxis occurs with no external allergen triggers and can be very frustrating to manage. Epinephrine is treatment of choice.