Final answer:
Anaphylaxis is a severe allergic reaction characterized by various symptoms and can be life-threatening. Epinephrine autoinjectors are used to control the immune reaction and provide immediate treatment.
Step-by-step explanation:
Anaphylaxis is a severe allergic reaction that can be life-threatening. It is a systemic reaction characterized by a massive release of histamines, leading to various symptoms such as a drop in blood pressure, changes in heart rate, shortness of breath, and swelling of the tongue and throat. Patients with a history of anaphylaxis may carry an epinephrine autoinjector, which helps to control the immune reaction and can be lifesaving. Epinephrine constricts blood vessels, relaxes smooth muscles in the lungs, and reduces swelling that may block the airways.