Anaphylaxis: Clinical approach and differential diagnosis

The clinical presentation of anaphylaxis may be extremely diverse depending upon the nature and route of allergen exposure, age of the affected individual, and other physiological factors including co-morbidities and concomitant drug intake. A carefully elicited, detailed history is necessary for the diagnosis of anaphylaxis and to differentiate between many conditions that may present similarly. This is necessary in order to optimally manage this potentially fatal but often preventable condition. In this chapter, we will discuss the clinical presentation and various conditions that can masquerade as anaphylaxis. The clinical and pathognomonic features and diagnostic investigations for these conditions will be presented. Clinical vignettes have been incorporated to illustrate the varied conditions and presentations outlined in the chapter.