347 patients with acute non-specific low back and neck pain were randomized to receive guideline-recommended care with either a judicious short-course opioid analgesic regimen (n=174) or a placebo (n=173). The primary outcome of interest was pain intensity at 6 weeks measured using the Brief Pain Inventory (BPI) Pain Severity subscale. Secondary outcomes included BPI-pain severity at 2, 4, 12, 26, and 52 weeks, BPI physical functioning, Roland-Morris Disability Questionnaire (RMDQ), Neck Disability Index (NDI), Short Form-12 (SF-12) physical and mental scores, global perceived effect scale, incidence of serious and non-serious adverse events, risk of opioid misuse, concomitant medication use, resource consumption, compliance, and total hours off paid work. There were no significant differences between the opioid analgesic and placebo groups in pain intensity at 6 weeks and all other time points, except at 52 weeks, which showed significantly better pain scores in the placebo group. The risk of opioid misuse at 52 weeks was significantly higher in the opioid analgesic group. SF-12 mental scores at weeks 6 and 12 showed significantly better outcomes in the placebo group, whereas RMDQ scores at 6 weeks were significantly better in the placebo group. All other secondary outcomes were similar between the two groups.