Exanthematous diseases are a group of illnesses characterized by a widespread rash or skin eruption. These conditions are often caused by viral infections, such as those associated with measles, rubella, or chickenpox. The rash typically appears after other symptoms, like fever or fatigue, and can vary in appearance and severity. These diseases are most common in children but can affect people of all ages. While many exanthematous diseases are mild and resolve on their own, some can lead to complications. Vaccination, such as the MMR vaccine for measles, mumps, and rubella, is an effective way to prevent many of these illnesses.