Inter-Site Inclusion Criteria:  Adult (> 18 years) men and premenopausal women; On stable medication for pain management for 3 months or more with no anticipated changes during the 10-weeks of this trial; Moderate pain at baseline (i.e., a score of 4-8 on a 10-point numeric rating scale) to prevent floor and ceiling effects. Can commit the use of two forms of effective contraception (e.g., barrier methods), or one highly effective method, including abstinence, intrauterine device, intrauterine system (IUS), vasectomy, tubal ligation, or hormonal contraceptive (e.g., combined oral contraceptives, patch, vaginal ring, injectables, and implants)  Intra-Site Inclusion Criteria:  Surrey, BC: Men and women with primary neuropathic pain - pain arising as a direct consequence of a lesion or disease affecting the central or peripheral nervous system - will be eligible. Neuropathic pain will be screened for using a score of 3+ on the Douleur Neuropathique 4 Interview, and confirmed through investigation (e.g., electromyography). Calgary, AB: Women with chronic (intermittent or constant) pelvic musculoskeletal pain (i.e., located primarily in the pelvic region and reproducible on palpation of the pelvic floor) who have not received a hysterectomy will be eligible. Women with a primary diagnosis of endometriosis, dysmenorrhea, functional bowel disorder, interstitial cystitis, fibromyalgia or sacroiliac instability as defined by European Guidelines, will be excluded. Carbonear NL: Men and women with primary musculoskeletal pain of back, neck, or shoulder origin will be eligible. Pain will be assessed using the BPI-SF and confirmed through physical examination.  Exclusion Criteria:  Positive urine pregnancy test or contemplating pregnancy; Concurrent use of another nasal spray; Nasal pathology (e.g., ears, nose, and throat diagnosis); Diabetes insipidus; Current diagnosis or history of cancer Significant unmanaged psychopathology (e.g., severe depression as indicated by a score ≥ 15 on the Patient Health Questionnaire -9) due to its inverse association with patient adherence to procedures; and Receiving hormone treatment for gender-related motivations. documented cardiovascular event (e.g., myocardial infarction) known prolongation of the QTc interval; 10) known hypersensitivity to oxytocin known latex allergy known or suspected renal impairment.