This excerpt from Outdoor Emergency Care: A Patroller’s Guide to Medical Care provides a detailed overview of allergies and anaphylaxis for OEC technicians. It explains the immune system's response to allergens, the various routes of allergen entry, and common causes of allergic reactions. The text categorizes allergic reactions by severity, outlining the signs and symptoms of mild, moderate, and severe (anaphylactic) reactions. Furthermore, it details patient assessment techniques for suspected allergic reactions and provides step-by-step instructions on how to properly administer epinephrine using an auto-injector.