Reye's syndrome is an extremely serious acute condition that may attack all major organs of the body, but particularly the brain and liver. Rapid buildup of fatty deposits in the liver can cause liver failure, but what makes Reye's so dangerous is inflammation of the brain. Reye's syndrome usually affects children between 4 and 12 years of age, although it has also been observed in adults.
Fortunately, Reye's syndrome is very rare and becoming rarer. Most cases involve children who have taken acetylsalicylic acid* (ASA, e.g., Aspirin®) for the flu, another respiratory infection, or chickenpox. The number of cases each year has dropped dramatically since its peak at 555 cases in 1980 and is directly due to an increase in awareness to not give ASA or other products containing salicylates to children and adolescents.