Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 1 2 2015 10 03 50 54 EN Nahid Manouchehrian Department of Anesthesiology and Critical Care, Fatemieh Hospital, Hamadan University of Medical Sciences, Hamadan, Iran. Ali Mohammadian Department of Anesthesiology and Critical Care, Ardebil University of Medical Sciences, Ardebil, Iran. Mohammad Sadegh Sanie Jahromi Department of Anesthesiology and Critical Care, Jahrom University of Medical Sciences, Jahrom, Iran. Nasrin Faridi Tazeh kand Department of Anesthesiology and Critical Care, Arash Women’s Hospital, Tehran University of Medical Sciences, Tehran, Iran. Mehdi Sanatkar Department of Anesthesiology and Critical Care, Razi Hospital, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 03 2015 10 03 Background: In most operating and recovery rooms, shivering is controlled by the use of humidifiers, warming blankets, and inhalation of humidified heated oxygen. However, pharmacological control is an effective alternative treatment modality. This study was designed to compare the efficacy of tramadol versus meperidine in the treatment of shivering after spinal anesthesia. Methods: In a double-blind randomized clinical trial, we studied 70 obstetric patients with ASA class  I or II who had shivering following spinal anesthesia (SA) with 0.5% bupivacaine. All patients were randomly allocated to one of the two groups receiving tramadol 0.5 mg/kg (group T, n = 35), or meperidine 0.5 mg/kg (group M, n = 35). The onset of cessation of shivering, the efficacy of agents for treatment of shivering, hemodynamic variables, sedation score, pruritus, nausea and vomiting were assessed. Results: Shivering ceased after 2.57±2.26 and 6.24±4.76 minutes in group T and group M respectively (p=0. 03). The differences before and after injection of meperidine for the heart rate, respiratory rate and arterial oxygen saturation were significant (p<0.001). Nausea and vomiting occurred significantly more frequently in the meperidine group compared to the tramadol group (p<0.001). Conclusion: Tramadol is a more effective agent than meperidine in the treatment of post spinal shivering, with lower early side effects in obstetric patients.  https://aacc.tums.ac.ir/index.php/aacc/article/view/15 https://aacc.tums.ac.ir/index.php/aacc/article/download/15/199