Paracetamol (acetaminophen in the US) has an analgesic and anti-pyrogenic, but no anti-inflammatory effect. Although paracetamol is one of the most widely used drugs, the precise mechanism of action drug is still unclear. There is no real evidence of paracetamol having significant action on COX-1 and COX-2 enzymes. It is believed to have an action in the central nervous system, but whether this is via COX-enzymes, the nitric oxide system, the serotonergic system or the endocannabinoid system is unclear.




Check the following publications on the mystery of the mechanism:

What do we (not) know about how paracetamol (acetaminophen) works? (J Clin Pharm Therapeutics 2010;35(6):617–638).

The analgesic activity of paracetamol is prevented by the blockade of cannabinoid CB1 receptors. (Eur J Pharmacol. 2006;531(1-3):280-1).

Paracetamol is a popular analgesic drug because of its few adverse effects. Large doses and normal doses over a longer period, however, can cause severe hepatic and renal damage.


Most of the prostaglandin synthesis inhibitors also have anti-inflammatory actions.