Reye's syndrome, rare but life-threatening disease characterized by acute encephalopathy and fatty infiltration of internal organs, especially the liver. It occurs almost entirely in children under age 15. The cause is unknown, but the disease usually follows an acute viral infection (particularly influenza or chicken pox), especially when aspirin or other salicylates have been given. The symptoms, which occur about a week after the virus infection, are vomiting and disorientation; these may be followed by seizures, coma, and respiratory arrest. Treatment is directed toward reducing brain swelling, correcting blood chemistry changes due to liver damage, and providing respiratory support if needed. Doctors recommend that children be given acetaminophen rather than aspirin for viral infections or fever.