Epinephrine is a chemical that narrows blood vessels and opens airways in the lungs. These effects can reverse severe low blood pressure, wheezing, severe skin itching, hives, and other symptoms of an allergic reaction. Epinephrine injection is used to treat severe allergic reactions (anaphylaxis) to insect stings or bites, foods, drugs, and other allergens. Epinephrine is also used to treat exercise-induced anaphylaxis. Epinephrine auto-injectors may be kept on hand for self-injection by a person with a history of an severe allergic reaction. Epinephrine injection may also be used for purposes not listed in this medication guide.