Reye syndrome is a rare but very serious illness that causes brain swelling and liver damage. It can also affect all the body's organs. As the swelling in the brain increases, the pressure inside of the head may also increase. The increased pressure in the head causes nervous system changes in the child.
The condition is most common in children and teens who are recovering from a viral infection. Reye syndrome usually affects children between ages 4 and 12, but it can occur at any age.
Symptoms occur very suddenly. If Reye syndrome is diagnosed and treated early, many children recover fully. But if not treated quickly, Reye syndrome can cause a child to go into a coma, lead to brain damage, or cause death.