Sudden onset of respiratory or cardiovascular compromise, usually with a history of allergen exposure in sensitised individuals.
Skin rash, wheezing and inspiratory stridor, hypotension, anxiety, nausea, and vomiting are the cardinal signs and symptoms.
The diagnosis is clinical. Allergy testing is helpful only for secondary prophylaxis.
Securing the airway and initiating prompt treatment with epinephrine (adrenaline) may save lives.
Comorbidities (e.g., CAD and COPD) may pose a treatment challenge and warrant expert consultation
Anaphylaxis is an acute, severe, life-threatening allergic reaction in pre-sensitised individuals, leading to a systemic response caused by the release of immune and inflammatory mediators from basophils and mast cells. At least 2 organ systems are involved, such as the skin, the upper and lower airways, and the cardiovascular, neurological, and GI systems, in this order of priority or in combination. Allergy to medicines, food, immunotherapy, or insect stings is the most frequent cause. Similar symptoms caused by non-immunological mechanisms are termed anaphylactoid reactions.   
Department of Allergy and Immunology
Icahn School of Medicine at Mount Sinai
DAA is an author of a number of references cited in this monograph.
Assistant Professor of Anesthesiology
Department of Anesthesiology
Montefiore Medical Center
Albert Einstein College of Medicine
MHA is an author of a reference cited in this monograph.
Dr Doerthe Adriana Andreae and Dr Michael Henning Andreae would like to gratefully acknowledge Dr Andrea Vereda, a previous contributor to this monograph. AV declares that she is currently employed by Almirall SA, which manufactures Kestin (ebastine, a second-generation antihistaminic). AV wrote the main content of this topic before taking up this appointment.
Family Medicine and Community Health
University of Massachusetts Medical School
FJD declares that he has no competing interests.
Assistant Professor of Pediatrics
Mount Sinai School of Medicine
WS declares that he has no competing interests.
Visiting Consultant in Allergy
Addenbrooke’s Hospital NHS Trust
LY declares that he has no competing interests.
Department of Immunology
Epsom & St Helier University Hospitals NHS Trust
GH declares that he has no competing interests.
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