Hand-foot-and-mouth disease is caused by the Coxsackie virus (a member of the Enterovirus family). The throat and tonsils develop small ulcers while the hands, feet, and diaper area are affected by a rash with characteristic vesicles (very small blisters). This is usually a mild illness with the rash healing in 5 to 7 days.

The actual incidence is unknown, but hand-foot-and-mouth disease is a relatively common infection. Another coxsackie virus infection with a high incidence and related features is herpangina. This is characterized by painful ulcers in the mouth and throat, but does not show a rash on the hands, feet or buttocks.

The most important risk factor is age. The infection affects young children, but can be seen in adolescents and occasionally adults. The outbreaks occur most often in the summer and fall.