Paracetamol is thought to relieve pain by reducing the production of prostaglandins in the brain and spinal cord. Prostaglandins sensitise nerve endings, causing pain. By reducing their production paracetamol is thought to increase our pain threshold, so that although the cause of the pain remains, we can feel it less.

It is thought paracetamol reduces fever by affecting an area of the brain that regulates our body temperature (the hypothalamic heat-regulating center).

Paracetamol is about as effective as aspirin or ibuprofen at relieving mild to moderate pain and fever, but unlike these it has no anti-inflammatory effect.

Caffeine is a mild stimulant that helps reduce fatigue. Caffeine is also thought to enhance the painkilling effect of paracetamol.