This chapter looks at the pharmacology of pain control and begins by defining the most important terms used in the session, and discusses an important group of drugs—the non-steroidal anti-inflammatory drugs or non-steroidal anti-inflammatory drugs (NSAIDs). It considers the mechanisms of NSAIDs, their therapeutic uses and some of the side effects which can be associated with them and describes the use of opioids: how they work, their pharmacological properties, their effects, their therapeutic use and the problems of tolerance, withdrawal and dependence. The ability of aspirin to control pain occurs both through a peripheral and a central action. When aspirin inhibits the synthesis of prostaglandins in inflamed tissue it prevents the prostaglandins from sensitising the nociceptors. NSAIDs are weak analgesic drugs whose main action is to suppress inflammation and pain by blocking prostaglandin synthesi.