There's no doubt about it: Children's fevers are scary. Ninety-one percent of parents worry that one will harm their child, according to a recent study from researchers at the Johns Hopkins Bayview Medical Center, in Baltimore. Indeed, fevers account for nearly 30 percent of visits to the pediatrician. But although a fever in a very young baby is always cause for concern, in most children a high temperature won't cause neurological damage unless it tops 105°F -- which is very rare.
"Fever is not an illness but a sign that the immune system is fighting off an infection," says Lynn Smitherman, M.D., assistant professor of pediatrics at Wayne State University. "When viruses or bacteria attack the body, white blood cells come to the rescue by producing interleukin, a hormone that raises body temperature. In effect, this rise in body heat helps kill the germs that are making your child sick." There's also some evidence that a fever helps fight illness by lowering blood levels of iron, which may be needed by germs to survive.