NSAIDs inhibit cyclo-oxygenase (COX) (Fig 1).

Consequently, prostaglandin production is reduced and their protective effects on the stomach and kidney are lost, resulting in well described side-effects (gastric erosions and renal impairment).

The useful effects of NSAIDs are a result of COX inhibition and its place in the inflammatory response.

However, their use has been associated with thromboembolic side effects leading to the withdrawal of certain COX-2 inhibitors.