Q. How does epinephrine turn off an anaphylactic reaction? This seems rather amazing, since anaphylaxis affects so many body systems.
Dr. Sharma: The ability of epinephrine to treat the many signs of anaphylaxis is rather amazing. It acts on a number of receptors in the body to exert its effects.
First, it causes constriction, or tightening, of the blood vessels, which decreases swelling and also helps to increase blood pressure.
It also increases the heart’s contraction and heart rate, which can help to prevent or reverse cardiovascular collapse.
Epinephrine relaxes the muscles around the airways in the lungs, helping the airways to open up.
Finally, it prevents the release of additional allergic chemicals, which aids in stopping further progression of the reaction.
No other medicine acts on so many body systems, which is why epinephrine is the drug of choice for anaphylaxis.
Dr. Sharma is an allergist, clinical researcher and Assistant Professor of Pediatrics. He is Associate 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 the American Edition of Allergic Living  magazine. Questions submitted below will be considered for answer in the magazine.