OBJECTIVES: Our aim was to compare the costs and effects of post-surgical parecoxib plus opioid treatment with opioid only analgesia over 3 days. METHODS: The analgesic safety and efficacy of intravenous parecoxib was evaluated in a randomized, double-blind clinical trial. Patients undergoing major orthopedic, abdominal, gynecologic, or noncardiac thoracic surgery requiring anesthesia received either 40mg parecoxib on the day of surgery, then 20mg parecoxib every 12 hours for 3 days or matching placebo. Patients also received standard regimen of opioids on demand for supplemental analgesia. Placebo patients consumed significantly more opioids, had significantly higher mean pain ratings on each study day and reported significantly more opioid-related symptom distress than parecoxib patients. Effects were measured as the sum of pain intensity (SPI) scores over a 24 hour period. Once daily, using four-point scales, patients also rated their distress from opioid-related adverse events (AEs) in terms of frequency, severity, and degree of bother. An AE was defined as clinically meaningful event (CME) based on a severity rating of "severe'" or "very severe" for all AEs except confusion, which was defined by ratings from "moderate" to "very severe." A treatment model based on clinical practice in the UK obtained through a clinician panel was developed incorporating opioid use and impact of CMEs on resource use. RESULTS: Parecoxib achieved 1.36 days reduction in length of hospital stay, and 0.41 and 1.80 hours reduction in physician and nurse time, respectively. Parecoxib cost £16.25 over 3 days, however reduced the costs of opioid use by £0.21 and the cost of treatment of opioid-related CMEs by £429.80. Parecoxib also reduced SPI scores by 21.6 points over this period, therefore dominated opioid only analgesia. CONCLUSION: Parecoxib is useful adjunct to opioids in noncardiac surgical patients improving postoperative analgesic management, reducing opioid need, opioid-related AEs and lowering treatment costs.