Medication for Nausea and Vomiting from Viral Illness
For adults with viral gastroenteritis, ondansetron is the preferred first-line antiemetic due to its superior efficacy and safety profile, with no sedation or extrapyramidal side effects. 1, 2
Adults
First-Line Treatment
- Ondansetron 8 mg orally or IV is the recommended initial antiemetic for viral gastroenteritis-related nausea and vomiting 2
- Ondansetron is as effective as other antiemetics but avoids sedation and akathisia (restlessness) that occurs with dopamine antagonists 2
- This medication works by blocking serotonin 5-HT3 receptors in the gut and central nervous system 1
Alternative Options (Second-Line)
If ondansetron is unavailable or ineffective, consider:
- Metoclopramide 10-20 mg orally or IV every 4-6 hours - but monitor for akathisia that can develop within 48 hours 1, 2
- Prochlorperazine 10 mg orally or IV every 6 hours - also carries risk of akathisia 2
- Promethazine 12.5-25 mg orally every 4-6 hours - causes more sedation and has risk of vascular damage with IV administration, so reserve for when sedation is desirable 2
Critical Caveat
Antiemetics are NOT a substitute for fluid and electrolyte replacement - ensure adequate hydration first before or concurrent with antiemetic therapy 1
Children
Age-Specific Recommendations
- Ondansetron is recommended ONLY for children >4 years of age with acute gastroenteritis and vomiting that prevents oral rehydration 1, 3
- The purpose is specifically to facilitate oral rehydration therapy, not routine symptom control 3
- A single oral dose reduces vomiting and decreases immediate need for hospitalization or IV fluids 1, 4
Important Pediatric Considerations
- Ondansetron may increase stool volume/diarrhea as a side effect, but this does not outweigh the benefit of controlling vomiting 1, 3
- Do NOT use antiemetics in children <4 years of age - insufficient evidence and safety data 1
- Oral rehydration therapy remains the cornerstone of treatment and takes absolute priority over antiemetic use 3
Hydration Protocol for Children
- Begin oral rehydration solution (ORS) with 5 mL every minute using a spoon or syringe, gradually increasing as tolerated 3
- Replace ongoing losses with 10 mL/kg ORS for each vomiting or diarrhea episode 3
- Resume normal age-appropriate diet immediately upon adequate rehydration - do not delay feeding 1, 3
Medications to Avoid
Antimotility Agents
- Never give loperamide or other antimotility drugs to children <18 years with acute diarrhea 1
- Avoid antimotility agents in any patient with fever or bloody diarrhea due to risk of toxic megacolon 1
Droperidol
- Previously effective but now limited to refractory cases due to FDA black box warning for QT prolongation 2