Eruptive fever, also known as exanthematous fever, is a term used to describe a group of infectious diseases that are characterized by sudden onset of fever accompanied by a distinctive rash. Some of the common types of eruptive fever include measles, chickenpox, smallpox, and scarlet fever. While the term eruptive fever is widely used, there are other words that can be used to describe the same condition. These include exanthem, which refers to the rash accompanying the fever, and pyrexia, which is simply another term for fever. Other terms that are sometimes used to describe eruptive fever include cutaneous fever, eruptive exanthema, and febris exanthematosa.