Does opioid analgesia show a gender preference for females?

Recent evidence suggests that one of the factors that may influence the assessment and management of pain is a person's gender. However, only a limited amount of information exists on gender differences in responses to analgesic medications. Based on a review of the available literature published between 1966 and 1998, we suggest that opioids are better analgesics for women. The information in this paper comes predominantly from several studies on the use of patient-controlled analgesia for the management of postoperative pain. Additional information comes from our recent work that demonstrated a sexual dimorphism in oral surgery patients' responses to three different opioid analgesics that share the property of acting as agonists at the kappa-opioid receptor. The paper concludes with a discussion of the major recommendations for future research regarding the gender biology of pain.