Study objectives: Patients often present to the emergency department with nausea and vomiting. Droperidol has been established to be a cost-effective treatment. However, comparison of the doses commonly used has not been undertaken. Our primary interest is to compare the effectiveness of droperidol at 3 doses. A secondary purpose is to monitor the QTc for all patients receiving droperidol. Methods: This was a prospective, randomized study of droperidol as a treatment for nausea and vomiting set in an urban teaching hospital (>100,000 patient visits/year). All adult patients presenting with nausea and vomiting who were to receive an antiemetic intravenously were eligible. Exclusion criteria included pregnancy, mental handicaps, and QTc greater than 440 msec. Patients were randomized to receive 0.625 mg, 1.25 mg, or 2.5 mg of droperidol intravenously. Visual analog scales (VAS) assessed the patient's degree of nausea and somnolence at 0 and 60 minutes. Any extrapyramidal reactions and dysrhythmias were recorded. A rhythm strip was completed before and after treatment. Data were analyzed using descriptive statistics and analysis of variance. Results: A total of 26 patients have been enrolled thus far (0.625-mg group, n=6; 1.25-mg group, n=15; 2.5-mg group, n=5). The mean change in nausea VAS for droperidol 0.625 mg was −44.2 mm (95% confidence interval [CI] 9.9 to 78.4), for 1.25 mg was −30.4 mm (95% CI 19.0 to 41.7), and for 2.5 mg was −45.0 mm (95% CI 20.2 to 69.8; P=.34). The mean change in somnolence VAS for droperidol 0.625 mg was 0.0 mm (95% CI −26.5 to 26.5), for 1.25 mg was 4.8 mm (95% CI −12.6 to 22.5), and for 2.5 mg was 20.0 mm (95% CI 0 −56.5 to 60.5; P=.95). The mean change in QTc for 0.625 mg was −0.021 mm (95% CI −0.134 to 0.091), 1.25 mg was 0.013 mm (95% CI −0.009 to 0.034), and 2.5 mg was −0.055 mm (95% CI −0.293 to 0.183; P=.35). Adverse events occurred in 0 of 6 of the 0.625-mg group, 2 (13%) of 15 of the 1.25-mg group, and 1 (20%) of 5 of the 2.5-mg group (P=.54). Conclusion: Nausea and vomiting symptoms were reduced equally with the 3 droperidol doses. No significant change in QTc occurred for any group. The frequency of adverse events increased with larger droperidol doses.