Reye syndrome is a rare, possibly life-threatening condition that primarily affects children – most often those under 15 years old. Nearly half of all reported cases involve children under 5 years old, according to the Centers for Disease Control and Prevention (CDC).

The cause of Reye syndrome is unknown, although the use of aspirin or salicylate-containing medications in children and teenagers to treat viral infections (e.g., cold, flu, chickenpox) is associated with onset of the condition. It primarily causes damage to the brain and liver. Death occurs in 20 to 30 percent of reported cases.

Reye syndrome was identified in 1963, though the disease was first diagnosed as a unique illness in 1929, and the number of cases peaked in the 1960s and 1970s. Since 1980, the number of reported cases has dropped dramatically. Beginning in the 1980s, physicians warned parents away from using aspirin in children recovering from viral infections. This may have prevented some cases of Reye syndrome. In addition, other disorders now classified as inborn errors of metabolism have since been identified with similar symptoms. Children with these conditions might have been diagnosed with Reye syndrome in earlier decades.

Within a week of a viral illness, a child’s or teenager’s condition may appear to worsen. Symptoms of Reye syndrome include continual vomiting, lethargy and changes in a person’s mental status (e.g., disorientation, confusion, irritation, argumentative and/or aggressive behavior). Vomiting may not occur in infants with Reye syndrome, although additional symptoms (e.g., diarrhea, irregular breathing) may occur.

Parents and other caregivers who believe a child may have Reye syndrome should seek immediate medical attention because symptoms may progress rapidly. Early identification can help reduce the risk of long-term complications (e.g., brain damage, coma) and death. Diagnosis may be made if a child has recently had a viral illness, has taken aspirin, there is evidence of liver dysfunction and changes in mental status and other conditions have been ruled out. Many laboratory tests may be involved in the diagnosis, especially to rule out metabolic causes. Tests may include liver function tests, serum ammonia test (blood test that measures the levels of the waste product ammonia) liver biopsy, spinal tap and/or imaging tests.

There is no known cure for Reye syndrome. Most often, supportive care for patients with the syndrome is provided in a hospital. The type of treatment depends on the condition of the patient and may include efforts to reduce swelling of the brain, balance the patient’s nutrient and fluid levels, and aid breathing in cases of respiratory difficulty. Each patient’s level of recovery depends on the severity of the symptoms.