Roseola infantum, also known as sixth disease, is a common, mild, viral infection that can cause a temperature and rash in babies and young children. It is caused by a virus from the herpes group, but it does not cause other herpes infections like cold sores. Roseola commonly affects children aged between six months and two years, and 95% of children have been infected with it by the age of two. Roseola is contagious before the symptoms appear, so it is difficult to prevent its spread to others.

Symptoms of roseola include a sudden high temperature, which usually lasts between three to five days. Occasionally, a raised, red rash can develop when the childs temperature returns to normal. The rash appears on the body and spreads to the arms and legs, but it is rarely seen on the face. The rash generally lasts for two days and turns white (blanches) when pressed.

Most symptoms of roseola are so mild that parents do not even realize their child is infected with the virus, and roseola almost never requires any medical treatment. However, febrile seizures (normally harmless) can occur in some children. Roseola may cause serious complications in children with weakened immune systems. If your child is unwell with a fever and a skin rash (small bright red spots or purple spots or unexplained bruises) that does not turn to skin-color (blanch) when you press on it, this may be a sign of meningococcal infection.