Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis.

Anaphylaxis is an acute, potential life-threatening systemic allergic reaction that may have a wide range of clinical manifestations. Severe anaphylaxis and/or the need for repeated doses of epinephrine to treat anaphylaxis are risk factors for biphasic anaphylaxis. Antihistamines and/or glucocorticoids are not reliable interventions to prevent biphasic anaphylaxis, although evidence supports a role for antihistamine and/or glucocorticoid premedication in specific chemotherapy protocols and rush aeroallergen immunotherapy. Evidence is lacking to support the role of antihistamines and/or glucocorticoid routine premedication in patients receiving low- or iso-osmolar contrast material to prevent recurrent radiocontrast media anaphylaxis. Epinephrine is the first-line pharmacotherapy for uniphasic and/or biphasic anaphylaxis. After diagnosis and treatment of anaphylaxis, all patients should be kept under observation until symptoms have fully resolved. All patients with anaphylaxis should receive education on anaphylaxis and risk of recurrence, trigger avoidance, self-injectable epinephrine education, referral to an allergist, and be educated about thresholds for further care.