Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 0 0 2026 02 25 1519 1519 EN Milad Masaeli Water and Electrolyte Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. & Department of Anesthesiology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. & Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Kazhal Mirzaee Tabar Student Research Committee, Tehran University of Medical Sciences, Tehran, Iran. Setayesh Sindarreh Epidemiology and Biostatistics Department, Health School, Isfahan University of Medical Sciences, Isfahan, Iran. & Cancer Prevention Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Zahra Ghasemi Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Iran. Tayyebe Faraji Department of Pediatrics, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. 2025 12 11 2025 12 27 Background: Shivering is a common and distressing complication of spinal anesthesia for cesarean section. While intrathecal meperidine is an effective prophylactic agent, its side effect profile prompts the search for alternatives. Intravenous acetaminophen has been proposed as a potential option due to its central antipyretic effect, but its efficacy compared to meperidine remains unclear. This study aimed to compare the efficacy and safety of prophylactic intrathecal meperidine versus intravenous acetaminophen for preventing shivering during cesarean section under spinal anesthesia. Methods: In this triple-blind randomized controlled trial, 151 parturient (ASA II) scheduled for elective cesarean section under spinal anesthesia were allocated to three groups: 1) PARA group (n=49): received 1 g IV acetaminophen; 2) MEP-IT group (n=49): received 0.1 mg/kg intrathecal meperidine; 3) Control group (n=51): received placebo. The primary outcome was the incidence of clinically significant shivering (Grade ≥2). Secondary outcomes included shivering onset time, hemodynamic parameters, and adverse effects. Results: The incidence of shivering was significantly lower in the MEP-IT group (24.5%) compared to both the PARA and control groups (49% each; P<0.0001). Shivering onset occurred significantly earlier in the PARA group (median: 5 minutes) than in the MEP-IT and control groups (median: 45 minutes; P<0.001). The PARA group exhibited a pronounced and sustained reduction in mean arterial pressure (MAP) and required vasopressor support more frequently (43%) than the control group (19%). Conclusion: Intrathecal meperidine is highly effective for shivering prophylaxis. Our study showed that although intrathecal meperidine is more effective than intravenous pracetamol in preventing shivering after spinal anesthesia, paracetamol not only has no preventive effect compared to the control group, but also has higher hypotension and calls for additional studies. https://aacc.tums.ac.ir/index.php/aacc/article/view/1519