Highlights
- Adding either acetaminophen or hydromorphone to ibuprofen did not result in a clinically significant reduction in pain scores for children with acute musculoskeletal injuries compared to ibuprofen alone.
- The primary efficacy outcome of self-reported pain scores at 60 minutes showed no statistical difference between treatment groups (P = .78).
- The use of hydromorphone was associated with a nearly five-fold increase in adverse events compared to non-opioid regimens.
- Current evidence supports the use of ibuprofen monotherapy as a sufficient first-line approach for nonoperative pediatric limb injuries.
Background: The Challenge of Pediatric Musculoskeletal Pain
Acute musculoskeletal (MSK) injuries, such as fractures, sprains, and strains, are among the most common reasons for pediatric emergency department visits. For decades, clinicians have grappled with the challenge of providing adequate analgesia for moderate to severe pain in this population. While ibuprofen is widely accepted as a first-line therapy due to its anti-inflammatory and analgesic properties, clinical observations have suggested that up to two-thirds of children continue to experience significant discomfort after monotherapy.
To address this unmet medical need, many clinicians have adopted a multi-modal approach, frequently adding acetaminophen (paracetamol) or oral opioids to ibuprofen. However, the efficacy of these additive strategies for acute MSK pain has remained largely anecdotal or extrapolated from adult data. Given the ongoing opioid crisis and the need for rigorous safety profiles in pediatric medicine, clarifying whether these combinations actually improve patient outcomes is of paramount importance.
Study Design and Methodology
The No OUCH (Oral Use of Analgesics for Children) trials were designed as two randomized, double-masked, placebo-controlled trials. Conducted between April 2019 and March 2023, the research took place across six university-affiliated, tertiary care pediatric emergency departments in Canada. The study focused on a cohort of 699 children aged 6 to 17 years who presented with nonoperative acute limb injuries occurring within the previous 24 hours.
Participants and Inclusion Criteria
To be eligible, participants had to report a verbal numerical rating scale (vNRS) pain score of 5 or more out of 10. This threshold ensured that the study targeted children experiencing moderate to severe pain who might theoretically benefit from intensified analgesia.
Intervention Protocols
The researchers utilized two parallel trials to evaluate different additive agents:
- The Opioid Trial: Randomized participants to receive ibuprofen plus hydromorphone (0.05 mg/kg), ibuprofen plus acetaminophen (15 mg/kg), or ibuprofen monotherapy.
- The Non-Opioid Trial: Randomized participants to receive ibuprofen plus acetaminophen or ibuprofen monotherapy.
In all arms, ibuprofen was dosed at a standard 10 mg/kg (maximum 600 mg). The maximum doses for acetaminophen and hydromorphone were 1000 mg and 5 mg, respectively. The primary efficacy endpoint was the change in self-reported vNRS pain scores at 60 minutes post-administration.
Key Findings: No Superiority for Combination Therapy
The results of the pooled analyses were striking in their consistency. Despite the theoretical benefit of combining medications with different mechanisms of action, the trials found no significant difference in pain reduction across any of the treatment groups.
Primary Efficacy Outcomes
At the 60-minute mark, the mean vNRS scores were 4.8 in the ibuprofen-hydromorphone group, 4.6 in the ibuprofen-acetaminophen group, and 4.6 in the ibuprofen-only group. With a p-value of .78, the differences were statistically insignificant. Furthermore, none of the combinations met the minimal clinically important difference (MCID) of 1.5 points on the vNRS scale relative to monotherapy.
Safety and Adverse Events
While efficacy was uniform, the safety profiles varied significantly. The primary safety endpoint—the proportion of children with any adverse event—was substantially higher in the opioid group. Any adverse event occurred at a rate of 28.2% in the ibuprofen plus hydromorphone group, compared to only 6.1% in the ibuprofen plus acetaminophen group and 5.8% in the ibuprofen alone group. Common side effects in the hydromorphone group included nausea, vomiting, and dizziness. Fortunately, no serious adverse events were reported in any group.
Expert Commentary and Clinical Implications
The findings from the No OUCH trials challenge the common practice of “stacking” analgesics for pediatric limb injuries. From a clinical perspective, these results suggest that for the majority of nonoperative MSK injuries, the addition of a second agent within the first hour of treatment does not provide a meaningful benefit.
Mechanistic Insights
One possible reason for the lack of additive effect is the pharmacokinetics of oral medications. The 60-minute window, while standard for emergency department assessments, may not capture the peak effect of all three drugs when used in combination. However, even if delayed benefits exist, the immediate need for pain relief in an acute setting is not met more effectively by the combination. The study also highlights that ibuprofen’s inhibition of cyclooxygenase (COX) enzymes may be the primary driver of relief in inflammatory MSK pain, rendering the central analgesic effects of acetaminophen or opioids redundant in this specific clinical context.
Opioid Stewardship
The four-fold increase in adverse events associated with hydromorphone, without any concomitant increase in efficacy, provides a strong argument against the routine use of opioids for acute pediatric MSK pain. In an era where healthcare systems are striving to reduce opioid exposure, these data provide clinicians with the evidence needed to confidently opt for non-opioid monotherapy.
Conclusion and Practical Recommendations
The No OUCH trials provide high-quality evidence that for children with acute, nonoperative musculoskeletal injuries, ibuprofen monotherapy is as effective as combinations involving acetaminophen or hydromorphone. Given the increased risk of adverse effects associated with opioids and the lack of added benefit from acetaminophen, clinicians should prioritize ibuprofen at appropriate weight-based doses (10 mg/kg) as the mainstay of treatment.
Future research may need to explore whether different timing, different types of injuries (e.g., specific fracture types), or alternative delivery methods (such as intranasal fentanyl) offer better outcomes for those who do not respond to initial ibuprofen.
Funding and Clinical Trial Information
The study was funded by the Canadian Institutes of Health Research (CIHR). ClinicalTrials.gov Identifier: NCT03767933.
References
Ali S, Klassen TP, Candelaria P, et al. Acetaminophen (Paracetamol) or Opioid Analgesia Added to Ibuprofen for Children’s Musculoskeletal Injury: Two Randomized Clinical Trials. JAMA. 2026 Jan 8:e2525033. doi: 10.1001/jama.2025.25033. Epub ahead of print. PMID: 41505155; PMCID: PMC12784265.