Acetaminophen, also known as paracetamol, is a widely used over-the-counter analgesic pain reliever and antipyretic fever reducer drug. It is commonly used to treat mild to moderate pain and fever. The exact mechanism of action of acetaminophen is not completely understood, but it is believed to work through several biochemical pathways in the human body.1. Inhibition of cyclooxygenase COX enzymes: Acetaminophen is thought to primarily exert its analgesic and antipyretic effects by inhibiting the activity of cyclooxygenase COX enzymes, specifically COX-1 and COX-2. These enzymes are responsible for the synthesis of prostaglandins, which are lipid compounds that play a role in inflammation, pain, and fever. By inhibiting COX enzymes, acetaminophen reduces the production of prostaglandins, thereby alleviating pain and fever.2. Central nervous system CNS actions: Acetaminophen may also act within the central nervous system to produce its analgesic effects. It is believed to increase the pain threshold by inhibiting the synthesis of prostaglandins in the CNS, as well as modulating the activity of certain neurotransmitters, such as serotonin, which are involved in pain perception.3. Antioxidant activity: Acetaminophen has been shown to have some antioxidant properties, which may contribute to its analgesic effects. It can scavenge reactive oxygen species ROS and reactive nitrogen species RNS , which are molecules that can cause cellular damage and contribute to inflammation and pain.4. Endocannabinoid system: Some studies suggest that acetaminophen may interact with the endocannabinoid system, a complex cell-signaling system involved in various physiological processes, including pain and inflammation. Acetaminophen may increase the levels of anandamide, an endocannabinoid that has analgesic and anti-inflammatory properties, by inhibiting its degradation.In summary, acetaminophen works in the human body through multiple biochemical pathways, including the inhibition of COX enzymes, modulation of neurotransmitters in the CNS, antioxidant activity, and interaction with the endocannabinoid system. These actions collectively contribute to its analgesic and antipyretic effects.