Inborn errors of metabolism are disorders of metabolism that occur when cells are unable to produce proteins or enzymes which are needed to change certain chemicals into others. Some of the clinical and laboratory features of the syndrome can mimic those disorders found in metabolic disorders, making it difficult to establish an exact diagnosis. Reye's syndrome should be suspected if a pattern of certain symptoms appears either during or after a viral illness. Vomiting is often the first sign of Reye's syndrome, except for children under two who may have diarrhea or hyperventilate. The duration varies according to the severity of the disease.
Symptoms can range from mild to serious, possibly progressing to death.
However, its progression can also stop at any stage allowing for full recovery in five to ten days. Early diagnosis is vital. Unless the individual with Reye's syndrome is properly diagnosed and treated successfully, death is common and may occur in only a few days. The earlier the diagnosis and treatment, the better the chance of survival. There is a 90 percent chance of recovery for those diagnosed early and only a 10 percent chance of recovery for those diagnosed late.