Background: Considering undesirable postoperative pain in recovery phase and many side effects of narcotics, the preemptive analgesic effect of oral dextromethorphane on cholecystectomized patients was studied in this study.

Material and Methods: In this double blind, randomized, clinical trial on 44 patients in Shari’ati Hospital, Tehran University of Medical Sciences, 22 patients received placebo and 22 received 45 mg oral dextromethorphane 2 hours pre-operation. The anesthesia method was the same in both groups. Visual analog scale (VAS) for pain was recorded for each group in 1, 6 and 24 hours. Used morphine amount was recorded. As dextromethorphane causes drowsiness the patient's alertness was also recorded with Ramsey scores post- operation. Data were analyzed using t-test, Chi-square, and Mann-Whitney-U-tests.

Results: Mean postoperative pain intensity was 9.55 in case and 8.33 in control group respectively. This was statistically significant but limited only in the first postoperative hour. No difference was observed in 6^th, 24^th hour pain, sedation, and alertness between the groups.

Conclusion: Premedication with 45 mg oral dextromethorphane decreases post operative pain in first hour, so it can be used as an alternative analgesic drug along with narcotics.