Smoking and pain: pathophysiology and clinical implications.

Cigarette smoke, which serves as a nicotine delivery vehicle in humans, produces profound changes in physiology. Experimental studies suggest that nicotine has analgesic properties. However, epidemiologic evidence shows that smoking is a risk factor for chronic pain. The complex relationship between smoking and pain not only is of scientific interest, but also has clinical relevance in the practice of anesthesiology and pain medicine. This review will examine current knowledge regarding how acute and chronic exposure to nicotine and cigarette smoke affects acute and chronic painful conditions. It will cover the relevant pharmacology of nicotine and other ligands at the nicotinic acetylcholine receptor as related to pain, explore the association of cigarette smoking with chronic painful conditions and potential mechanisms to explain this association, and examine clinical implications for the care of smokers with pain.