Acetylsalicylic acid is a synthetic chemical compound that is used inmedications to treat pain, inflammation, and fever. It works by blockingthe body's production of compounds that cause pain, swelling, and fever, andalso helps prevent blood clots from forming in thearteries. Acetylsalicylic acid is considered one of the safest and mosteffective medicines in the world and is included on the WHO's List of EssentialMedicines.