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Intravenous Acetaminophen for the Management of Short-Term Post-Operative Pain: A Review of Clinical Effectiveness and Cost-Effectiveness

Last updated: October 12, 2018
Project Number: RC1023-000
Product Line: Rapid Response
Research Type: Drug
Report Type: Summary with Critical Appraisal
Result type: Report


  1. What is the clinical effectiveness of intravenous acetaminophen for patients with post-operative pain?
  2. What is the cost-effectiveness of intravenous acetaminophen for patients with post-operative pain?

Key Message

Evidence identified from seven systematic reviews was limited in methodological quality and was heterogeneous regarding patient populations, comparators, and time and duration of intravenous acetaminophen administration. One SR found that IV acetaminophen was superior to placebo in the proportion of adult patients undergoing any surgical procedure achieving at least 50% pain relief four or six hours after administration of IV medication. The remaining findings measuring difference in pain scores at various points in the post-operative period were inconsistent, limiting the ability to draw firm conclusions, however overall, the evidence suggests that IV acetaminophen may provide effective pain relief for those undergoing orthopedic surgeries (particularly knee and hip arthroplasty). There was no significant difference in pain scores comparing IV acetaminophen to placebo in adult patients undergoing abdominal surgery. The addition of IV acetaminophen to multimodal analgesia may reduce both opioid consumption and pain scores following hip and knee arthroplasty, however more randomized trials are needed to confirm this finding. In studies that assessed differences in hospital length of stay, there was no difference found in adding IV acetaminophen to a multimodal pain strategy.There was no evidence to show that IV acetaminophen performed better than active comparators such as IV NSAIDs, which are used sparingly in Canadian practice, or IV opioids. There was a consistent trend amongst studies showing an overall decrease in opioid consumption with the use of IV acetaminophen; however the magnitude of this decrease is unknown (and thus clinical significance is also unknown). Considering the oral administration of acetaminophen or other pain relieving drugs may not be well-tolerated in the immediate post-operative periods, IV acetaminophen may be an additional option to provide pain relief for those undergoing surgeryNo studies on the cost-effectiveness of IV acetaminophen peri-operatively or immediately post-operatively were identified and the clinical studies mainly focused on short-term outcomes.