Anaphylaxis Epipen in Thigh

Anaphylaxis is one of the most under-appreciated and under-treated conditions in the Emergency Department. A common misperception is that you need hypotension to diagnose it. Below is a brief summary of the diagnostic criteria and ED treatment protocol. Immediate administration of IM epinephrine is critical.

A major challenge is deciding which patients can go home and which need to be admitted, because of the risk of “rebound” or a biphasic anaphylactic response. This may occur as late as 72 hours later, but typically occur within the first 24 hours. There isn’t a good answer for this.

What’s your practice in dispositioning these patients? Personally, I admit at least those patients who present with severe hypotension, require more than 1 epinephrine dose, or have poor social support.

NOTE: Unlike the photo on the top, warn patients NOT to rest their thumb on the device because of the risk inadvertent needle puncture.

PV Card: Anaphylaxis

Adapted from [1, 2] Go to ALiEM (PV) Cards for more resources.


  1. Arnold J, Williams P. Anaphylaxis: recognition and management. Am Fam Physician. 2011;84(10):1111-1118. [PubMed]
  2. Simons FER. Anaphylaxis. Journal of Allergy and Clinical Immunology. 2010;125(2):S161-S181. doi: 10.1016/j.jaci.2009.12.981
Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at Bio:
Michelle Lin, MD