Ondansetron in the Field
Objective: Use ondansetron as a comfort and aspiration-prevention tool — after you thought about ACS, head injury, and the QT.
Why This Is Hard
They vomit and someone wants ondansetron before a 12-lead. Inferior STE and a head injury both vomit. The drug is fine when the protocol says so. The diagnosis still comes first.
- 12-lead if this could be ACS. Glucose if this could be hypo.
- ODT vs IV is packaging. This site does not publish milligrams.
- QT-prolonging polypharmacy (other antiemetics, some psych meds) is a caution — follow your card.
Field Rules (Education)
- Use: nausea/vomiting to protect the airway and make transport possible.
- Not a substitute for turning them, suction, or treating shock.
- QT: ondansetron can prolong QT. Unstable dysrhythmia history or lots of QT drugs — protocol/OLMC.
- Kids: many systems use it. Follow pediatric protocol, not adult memory.
Field Pitfalls
- Ondansetron instead of a 12-lead in diaphoretic epigastric pain.
- Stacking QT drugs without a thought.
- Calling the call done because they stopped vomiting.
Practice
60-second drill
Partner: (1) isolated motion sickness, clean story; (2) diaphoretic epigastric vomiting. Ondansetron vs 12-lead first.
Related: STEMI, Abdominal pain.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; protocol still wins
- FDA ondansetron QT safety communication — QT caution — protocol owns whether and how you give it
- FDA labeling includes QT caution. Follow your antiemetic protocol.
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.