An EpiPen is an auto-injector device designed to deliver a single dose of the drug epinephrine and is prescribed to treat life threatening allergic reactions called anaphylaxis. Epinephrine is the first-line treatment for anaphylaxis and is administered with the EpiPen Auto-Injector. EpiPen is indicated to treat emergency cases of anaphylaxis in people at risk for allergic reactions. It is used only as an emergency supportive therapy for immediate self-administration. You should always seek medical attention following a reaction and use of an epipen.