Intravenous vs Oral Acetaminophen for Analgesia After Cesarean Delivery: A Randomized Trial

Pain Med. 2019 Aug 1;20(8):1584-1591. doi: 10.1093/pm/pny253.


Objective: Examination of postoperative analgesia with intravenous and oral acetaminophen.

Design: Prospective, three-arm, nonblinded, randomized clinical trial.

Setting: A single academic medical center.

Subjects: Parturients scheduled for elective cesarean delivery.

Methods: This trial randomized 141 parturients to receive intravenous acetaminophen (1 g every eight hours, three doses), oral acetaminophen (1 g every eight hours, three doses), or no acetaminophen. All patients received a standardized neuraxial anesthetic with intrathecal opioids and scheduled postoperative ketorolac. The primary outcome, 24-hour opioid consumption, was evaluated using the Kruskal-Wallace test and Tukey-Kramer adjustment for multiple comparisons. Secondary outcomes included 48-hour opioid consumption, first opioid rescue, pain scores, patient satisfaction, times to ambulation and discharge, and side effects.

Results: Over 18 months, 141 parturients with similar demographic variables completed the study. Median (interquartile range) opioid consumption in intravenous morphine milligram equivalents at 24 hours was 0 (5), 0 (7), and 5 (7) for the intravenous, oral, and no groups, respectively, and differed between groups (global P = 0.017). Opioid consumption and other secondary outcomes did not differ between the intravenous vs oral or oral vs no groups. Opioid consumption was reduced at 24 hours with intravenous vs no acetaminophen (P = 0.015). Patients receiving no acetaminophen had 5.8 times the odds of consuming opioids (P = 0.036), consumed 40% more opioids controlling for time (P = 0.041), and had higher pain scores with ambulation (P = 0.004) compared with the intravenous group.

Conclusions: Intravenous acetaminophen did not reduce 24-hour opioid consumption or other outcomes compared with oral acetaminophen. Intravenous acetaminophen did decrease opioid consumption and pain scores compared with no acetaminophen.

Trial registration: NCT02487303.

Keywords: Acetaminophen; Analgesia; Analgesics; Cesarean Section; Non-narcotic; Obstetrical; Pain; Postoperative.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Acetaminophen / administration & dosage*
  • Administration, Intravenous
  • Administration, Oral
  • Adult
  • Analgesics, Non-Narcotic / administration & dosage*
  • Analgesics, Opioid / therapeutic use*
  • Anesthesia, Spinal
  • Anti-Inflammatory Agents, Non-Steroidal / therapeutic use
  • Breakthrough Pain / drug therapy*
  • Breakthrough Pain / epidemiology
  • Cesarean Section*
  • Female
  • Humans
  • Ketorolac / therapeutic use
  • Pain Measurement
  • Pain, Postoperative / drug therapy*
  • Pregnancy
  • Young Adult


  • Analgesics, Non-Narcotic
  • Analgesics, Opioid
  • Anti-Inflammatory Agents, Non-Steroidal
  • Acetaminophen
  • Ketorolac

Associated data