Reye Syndrome is not contagious. It is a rare but serious condition that primarily affects children and teenagers recovering from a viral infection, such as the flu or chickenpox. It is characterized by swelling in the liver and brain, leading to potentially life-threatening complications. The exact cause of Reye Syndrome is unknown, but it has been linked to the use of aspirin during viral illnesses. Prompt medical attention is crucial for proper diagnosis and treatment of this non-contagious syndrome.