What are Epinephrine injections used for?

Epinephrine. "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) ." See: http://www.drugs.com/mtm/epinephrine-injection.html.