Ondansetron is safe and effective for prehospital treatment of nausea and vomiting by paramedics.

Unlabelled: OBJCTIVE: The objectives were to evaluate the safety and efficacy of ondansetron in the out-of-hospital treatment of undifferentiated nausea or vomiting.

Methods: Patients with severe nausea or intractable vomiting who were transported by paramedic-staffed ambulances in eight California counties were treated with intravenous (IV), intramuscular (IM), or oral dissolving tablet (ODT) administration of ondansetron. Data were collected prospectively for a six-month period using an online database. Prospectively defined outcome measures were 1) efficacy as measured by a quantitative visual analog nausea scale and 2) incidence of adverse effects. There were no control or placebo groups.

Results: Data was collected for 2072 patients, but one patient did not receive the medication. Therefore, Ondansetron was administered to 2,071 patients (3.7% of transported patients). Most patients were adult, with only 66 patients less than 18 years old. Of the 2,071 patients, 1,320 (64%) received IV administration, 77 (4%) received IM administration, and 674 (33%) received ODT administration of ondansetron. Intravenous administration resulted in the largest improvements in nausea scores (mean 4.4; 95% confidence interval [CI] 4.2, 4.5), followed by IM (mean 3.6; 95% CI 3.0, 4.3) and ODT (mean 3.3; 95% CI 3.1, 3.5). Overall, the mean decrease in nausea score was 4.0 (95% CI 3.9, 4.1; p < 0.001) on a 10-point scale. After medication administration, four patients had mild hypotension, one had hypertension, two had itching or rash, and one had a brief episode of supraventricular tachycardia that resolved spontaneously.

Conclusions: Ondansetron is safe and effective for out-of-hospital treatment of nausea and vomiting when administered by paramedics via the IV, IM, or oral route. When available to paramedics, ondansetron is used frequently.