Ondansetron


How it works: Acts on specific serotonin receptors targeting nerves in the intestinal tract. These nerves are responsible for bowel function.

Which symptoms does it help: Diarrhea.

How long it takes to see a benefit: Within one week.

FDA approved: N/A

Dosage: 4-8mg tablet or oral disintegrating tablet.

Special considerations or risks: Individuals should be monitored for cardiac conduction abnormalities as well as serotonin syndrome, especially among individuals taking serotonergic drugs. Monitor for decreased bowel activity, especially among individuals with risk factors for gastrointestinal obstruction.

Most common side effects: Constipation.

Recommendation: ACG suggests ondansetron for improvement in bothersome diarrhea among individuals with IBS.