Anaphylaxis is a severe allergic reaction that can include potentially deadly anaphylactic shock. Anaphylaxis develops within seconds to minutes after contact with an allergen (a substance that someone is allergic to). Signs and symptoms of anaphylaxis include a
- skin rash,
- nausea and vomiting,
- a rapid heart rate, and
- difficulty breathing.
Some of the allergens that can trigger an anaphylactic reaction can include insect bites, foods, and certain medications. Those who are at risk for anaphylactic reactions should carry a device for the immediate injection of epinephrine to treat anaphylaxis.
From 
References
Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.