Aspirin, also known as acetylsalicylic acid, is a nonsteroidal anti-inflammatory drug NSAID that works by inhibiting the production of certain chemical messengers called prostaglandins, which are responsible for pain, inflammation, and fever in the body.At the molecular level, aspirin exerts its effects by targeting an enzyme called cyclooxygenase COX . There are two main isoforms of this enzyme, COX-1 and COX-2. COX enzymes are responsible for converting arachidonic acid, a fatty acid found in cell membranes, into prostaglandins and other related compounds.Prostaglandins are involved in various physiological processes, including the mediation of pain, inflammation, and fever. They can also promote blood clotting and protect the stomach lining from the damaging effects of stomach acid.Aspirin works by irreversibly acetylating a serine residue in the active site of the COX enzymes, which prevents the binding of arachidonic acid to the enzyme. This, in turn, inhibits the production of prostaglandins and other related compounds, leading to a reduction in pain, inflammation, and fever.It is important to note that aspirin's inhibition of COX-1 can also lead to some side effects, such as gastrointestinal irritation and increased bleeding risk. This is because COX-1 is responsible for producing prostaglandins that protect the stomach lining and promote blood clotting. However, the overall benefits of aspirin in reducing pain and inflammation often outweigh these potential side effects for many individuals.