Anaphylaxis is a relatively common and potentially lethal emergency. Current definitions highlight the presence of allergic and allergic-like reactions with end organ damage. Diagnosis can be difficult, but present guidelines (FAAN) focus on sensitivity above specificity. The main aspects of management are early recognition and early epinephrine. First line treatment is intramuscular epinephrine, fluids and positioning. In refractory cases, increasing dose of epinephrine, norepinephrine, vasopressin, glucagon, methilene blue and ECMO are considerations. Patients with airway compromise require advanced management. Disposition depends on severity and access to follow-up. An epinephrine auto-injector is necessary. Biphasic reactions are rare but real, with unclear incidence.