Fever and rash.

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