Aspirin in action. Computer artwork showing how aspirin has its effect. Aspirin (acetylsalicylic acid) is converted to salicylic acid and acetic acid in the body. The binding of salicylic acid deactivates the cyclooxygenase enzyme and is how aspirin has its effect. The salicylic acid molecule (blue) is bound to the cyclooxygenase enzyme (orange) by the groups (silver) in the binding site. Aspirin is a non-steroidal anti-inflammatory drug (NSAID). It is taken as an analgesic (painkiller), antipyretic (reduces fever) and anticoagulant (prevents blood clotting).