A scattered skin rash. The skin is usually raised and red, or may be covered with scales, or crusts, or vesicles containing fluid. Eruptions differ in appearance: for example, the eruption of MEASLES is always distinguishable from that of CHICKENPOX. But the same disease may also produce different eruptions in different people; or in the same person in different states of health; or even on different parts of the body at one time.

Eruptions may be acute or chronic. Most of the acute eruptions belong to the exanthemata (see EXANTHEM): that is, they are bright in colour and burst out suddenly like a flower. These are the eruptions of SCARLET FEVER, measles, German measles (see RUBELLA), SMALLPOX and chickenpox. In general, the severity of these diseases can be measured by the amount of eruption. Some eruptions are very transitory, like nettle-rash, appearing and vanishing again in the course of a few hours. (See also SKIN, DISEASES OF.)