Background: Post-anesthetic shivering is the most common cause of patient discomfort during recovery with a prevalence of 5 to 65%. Post-anesthetic shivering can increase pain, oxygen consumption, and cardiac output. The aim of this study was to compare the efficacy of various classes of drugs for preventing post-anesthetic shivering.

Materials and Methods: In this double-blind clinical trial, patients undergoing elective laparotomy were randomly divided into six groups, 40 each. The patients, respectively, received hydrocortisone, ketamine, tramadol, magnesium sulfate, pethidine, and normal saline. All patients were observed for body temperature and shivering for 20 minutes after arrival to recovery room.

Results: Seventy patients in the pethidine group did not have shivering upon arrival to recovery room which was significantly higher than other groups (&chi2=0.00002). Also, the patients in the pethidine group did not shiver 10 and 20 minutes after arrival to recovery room that was significantly lower than other groups.

Conclusion: According to the results, it can be concluded that pethidine is more effective than other drugs in prevention of post-anesthetic shivering.