Reye's syndrome is most commonly associated with the ingestion of which substance?

Reye's syndrome is a serious condition that primarily affects children and is associated with the ingestion of acetylsalicylic acid, commonly known as aspirin. This syndrome is characterized by a combination of encephalopathy and fatty liver degeneration, and it often follows a viral infection, such as influenza or chickenpox. The mechanism behind this association is not fully understood, but the use of aspirin during viral infections in children has been noted to increase the risk of developing Reye's syndrome significantly.

The other substances listed, such as ibuprofen, paracetamol (acetaminophen), and naproxen, are non-steroidal anti-inflammatory drugs (NSAIDs) or analgesics that have not been shown to have the same association with Reye's syndrome. In fact, ibuprofen and paracetamol are typically recommended as safer alternatives to aspirin for pain and fever relief in children, particularly during viral infections, because they do not carry the same risk for this serious complication. Therefore, the consumption of acetylsalicylic acid is the primary concern when discussing the risk of Reye's syndrome.