Q: Why is the epinephrine auto-injector supposed to be given to the outer thigh as opposed to the upper arm, like a flu shot? Also, does it really matter if it’s the outer thigh or thigh front? I see people practicing as if it’s the thigh front in online videos all the time.
Dr. Sharma: Epinephrine is recommended to be given into the muscle, and not the subcutaneous tissue, because administration into the muscle will provide a more rapid increase in its concentrations in the blood and tissues.
This fast uptake of epinephrine is critical in the treatment of anaphylaxis.
As opposed to the upper arm, the thigh muscle is one of the body’s largest muscles with more blood supply, so it allows much faster absorption of the medication.
The outer thigh, versus the front of the thigh, is recommended because it provides a skin area with thinner tissue and less fat.
Dr. Sharma is an allergist, clinical researcher and associate professor of pediatrics. He is Chief of the Division of Allergy and Immunology at Children’s National Medical Center in Washington D.C. and Director of the Food Allergy Program. He co-authors “The Food Allergy Experts” column in Allergic Living magazine. Questions submitted will be considered for answer in the magazine.Submit a Question View all posts by this medical expert.