The combination of fever and rash comprises an extensive differential
diagnosis. Many of the causes of this presentation are life-threatenin
g. In this article, rashes are categorized as petechial, maculopapular
, vesicular, erythematous, and urticarial. Each type of rash is then d
ivided into infectious etiologies, both treatable and nontreatable, an
d noninfectious etiologies. It is usually possible to arrive at a work
able differential diagnosis when clinical, historical, and epidemiolog
ic factors are considered.