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Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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When the body develops an allergic reaction to some outside chemical or substance, it can activate its immune system to combat that substance. On occasion, there can be an excess response and multiple organ systems in the body can be affected and fail. This is known as anaphylaxis. Mast cells and basophils (a type of white blood cell) that contain histamine become unstable and leak their contents to affect the muscles of the lung, heart and blood vessels. These are smooth muscles that are part of the regulatory system of the body and are not under conscious control.

• The muscles that surround bronchial tubes go into spasm and cause wheezing and shortness of breath.
• The muscles that surround blood vessels dilate, causing blood pressure to drop.
• The histamine also causes flushing of the skin, urticaria (hives), vomiting and diarrhea.
• A variety of mechanisms cause the heart muscle to pump weakly and blood vessels to leak fluid.

The combination of these effects decrease blood flow and oxygen supply to cells in the body and can result in shock.

The most common causes of anaphylactic shock include allergic reactions to foods (especially peanuts), antibiotics, and bee and wasp stings. Children are often allergic to eggs, soy, and milk.

These allergens can cause the immune system to turn on the potential cascade to shock. Many patients have allergic reactions that are less severe and can just involve hives, but others can develop shortness of breath, wheezing, swelling of the tongue and mouth, and difficulty swallowing.

Initial treatment for major allergic reactions include calling 911 and activating the emergency response system. Medical interventions include injections of antihistamine like diphenhydramine (Benadryl), corticosteroids and adrenaline (epinephrine).

Patients with major allergic reactions must try to avoid the chemical trigger. They also often carry an Epipen (epinephrine injection kit) to inject themselves with epinephrine should an allergic reaction occur.

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