This chapter reveals that the issue of sex and gender differences in pain has become the focus of intense investigation at many levels of inquiry. Epidemiological and psychophysical studies reveal that the burden of pain is greater for women than men. Many chronic painful disorders show a higher female prevalence; only a few show a higher male prevalence. Women generally exhibit a greater sensitivity to nociceptive stimulation. There are, however, many exceptions to this generalization, with individual and situational variations being greater than sex differences. On the other hand, substantial sex and gender differences do appear to exist in the mechanisms by which pain is generated. The many factors that underlie these sex differences in pain mechanisms interact dynamically, developing and changing progressively throughout the life of each individual. Sex differences in sex steroid hormones, estrogen, progesterone, and testosterone, have been shown to contribute significantly to these differences, affecting wide regions of the brain and influencing the molecular, cellular, and integrative functions of many neuroactive agents.
