Ondansetron Use in Gastroenteritis

Introduction to Ondansetron

The American College of Physicians and the Infectious Diseases Society of America recommend ondansetron for the treatment of gastroenteritis with vomiting to facilitate oral rehydration, but not for the treatment of diarrhea itself 1, 2
Ondansetron is a 5-HT3 receptor antagonist designed to combat nausea and vomiting, not to stimulate intestinal motility or stop diarrhea, and it works by facilitating tolerance to oral rehydration in patients with acute gastroenteritis accompanied by vomiting 1, 2
Ondansetron is not a substitute for proper fluid and electrolyte therapy 1, 2

The American Academy of Pediatrics recommends that ondansetron can be given to children over 4 years old and adolescents with acute gastroenteritis accompanied by vomiting to facilitate oral rehydration 1, 2
Ondansetron should not be used routinely in children under 4 years old with acute gastroenteritis 2
Caution should be exercised in children with heart disease due to the risk of prolonged QT interval 2
For adults, ondansetron can be considered as additional therapy after the patient has been adequately hydrated 1, 2
Ondansetron is not a first-line therapy for diarrhea 1

The American College of Gastroenterology advises to avoid ondansetron in suspected or proven inflammatory diarrhea, or diarrhea with fever, due to the risk of toxic megacolon 2
Ondansetron should not be used in patients with ileus or gastrointestinal obstruction 1

During the first trimester of pregnancy, ondansetron is not a first-line therapy due to reports of congenital heart defects 3, 2
For irritable bowel syndrome with diarrhea (IBS-D), titrated doses of ondansetron have shown improvement in stool consistency, but this is a different context from acute gastroenteritis 4