Comparative Evaluation of Dexamethasone Versus Ondansetron For Prevention of Postoperative Nausea and Vomiting: A Prospective Observational Study

Background: Postoperative nausea and vomiting (PONV) remains one of the most common and distressing complications following surgical procedures, affecting patient satisfaction, recovery, and healthcare costs. Dexamethasone and ondansetron are widely used antiemetic agents, but comparative data regarding their efficacy in PONV prophylaxis remain inconsistent. This study aimed to compare the efficacy of dexamethasone versus ondansetron for prevention of PONV in patients undergoing various surgical procedures under general anesthesia.

Methods: A prospective observational comparative study was conducted from June 2024 to July 2025 at a tertiary care teaching hospital. A total of 240 patients aged 18-65 years undergoing elective surgeries under general anesthesia were included. Patients received either intravenous dexamethasone 8 mg (Group D, n=120) or ondansetron 4 mg (Group O, n=120) as per institutional protocol before induction of anesthesia. The primary outcome was the incidence of PONV during the first 24 hours postoperatively. Secondary outcomes included severity of nausea, number of vomiting episodes, requirement for rescue antiemetics, patient satisfaction scores, and adverse effects.

Results: The overall incidence of PONV was significantly lower in Group D compared to Group O (21.67% vs 35.83%, p=0.015). Dexamethasone demonstrated superior efficacy in preventing early PONV (0-6 hours: 15.00% vs 28.33%, p=0.012) and late PONV (6-24 hours: 10.83% vs 20.00%, p=0.045). The mean nausea severity score was significantly lower in the dexamethasone group (2.1±1.4 vs 3.2±1.8, p<0.001). Rescue antiemetic requirement was reduced in Group D (18.33% vs 32.50%, p=0.009). Patient satisfaction scores were significantly higher with dexamethasone (8.4±1.2 vs 7.6±1.5, p=0.001). No significant differences in adverse effects were observed between groups.

Conclusion: Dexamethasone 8 mg demonstrated better efficacy than ondansetron 4 mg for PONV prophylaxis in patients undergoing surgery under general anesthesia, with superior control of both early and late PONV, reduced rescue antiemetic requirements, and higher patient satisfaction without significant adverse effects.