A review of the literature was conducted to assess the association between oxytocin (OT) and pain. PsychInfo, PubMed, and Medline (EBSCO) research databases were searched for peer-reviewed articles written between 1950 and 2012. Of a total of 1166 articles returned, 50 (9 human, 33 animal, and 8 spinal cord samples) met full inclusion criteria and were included in the review. OT had a reliable effect as defined by increasing pain tolerance in 29 of 33 animal studies reviewed. This effect persisted across central and peripheral modes of administration and type of noxious stimulus used (eg, heat, electric). The results suggest that OT acts as an analgesic for acute pain in animals. Preliminary research with humans offers consistent evidence to suggest that OT decreases pain sensitivity, though the reliability and stability of such effects cannot yet be determined. Although the findings are encouraging, there is a need for methodologically rigorous work in humans where OT is administered centrally. Further research seems to be warranted as the existence of biologically and psychologically plausible mechanisms linking OT and pain have been well supported using animal models with limited but encouraging human research. Implications and recommendations are discussed. Findings from this research may inform therapeutic methods for the management of pain.

This study examined the effect of synthetic oxytocin delivered intranasally on acute pain sensitivity using a placebo-controlled, double-blind, within-participant crossover design. Thirty-seven (18 were male) pain-free young adults underwent two laboratory sessions separated by 1 week. Each session consisted of baseline, administration, second baseline, pain, and recovery phases, completed in a fixed order. Participants were given an intransal administration of 40 IU oxytocin or placebo. Blood pressure and heart rate (HR) were measured at 1-minute intervals throughout each phase. Pain was induced by submersing the nondominant hand in cold (2°C) water. Pain threshold, intensity, unpleasantness, and Short-Form McGill Pain Questionnaire-2 pain descriptors were rated immediately after pain testing. Mood was assessed using visual analog scales after baseline, second baseline, and pain phases. The second laboratory session was identical to the first, with the exception that a different nasal spray was administered. Participants reported lower pain intensity (50.57 [20.94] versus 56.73 [20.12], p = .047), pain unpleasantness (47.00 [27.24] versus 55.78 [22.46], p = .033), and Short-Form McGill Pain Questionnaire-2 pain descriptors (53.38 [31.18] versus 60.92 [31.17], p = .031) and higher pain threshold (45.70 [59.55] versus 38.35 [59.12], p = .040) after oxytocin administration relative to placebo. There was a nasal spray by phase interaction on HR (p = .006). Pain-related increase in HR was attenuated by oxytocin nasal spray. Systolic and diastolic blood pressure increased during pain testing but were unaffected by nasal spray. These results suggest that oxytocin can lead to decreased acute pain sensitivity.

Context. Many breast cancer survivors live with chronic neuropathic pain (CNP) after breast cancer treatment. Despite pharmacological management of CNP, many women continue to report disabling pain and reduced quality of life. Addressing pain with psychosocial interventions as an adjunct to pharmacological treatment is often recommended for CNP. Objectives. The purpose of this study was to compare the effects of group-delivered mindfulness-based stress reduction as compared to a waitlist control group among breast cancer survivors living with CNP. Methods. A randomized controlled trial design was applied, and outcomes collected included pain, emotional function, quality of life, and global impression of change. Results. A total of 98 women were randomized and included in analyses. The sample included 49 women in the mindfulness-based stress reduction group, and 49 women in the waitlist control group. The intervention group participants (mean age 51.3 years, standard deviation=11.4) and waitlist participants (mean age 55.1 years, standard deviation=9.6) reported an average pain duration of approximately three years. No significant differences were found on the primary outcome of the proportions of women with reduced pain interference scores from the time of randomization to 3 months after the intervention was received. No significant changes were found among secondary outcomes. Conclusion. Our randomized clinical trial did not find significant benefits of group-based mindfulness-based stress reduction for the management of CNP. The current study findings should be replicated and are important to consider given ongoing concerns that nonsignificant results of mindfulness-based stress reduction are often unpublished.