Antibiotics (Rifaximin)

How it works: Modifies the bacteria in the intestines and colon which leads to less severe and less frequent IBS symptoms.

Which symptoms does it help: Overall IBS symptoms, abdominal pain, bloating, and diarrhea.

How long it takes to see a benefit: Within 1-2 weeks.

FDA approved: IBS-D.

Dosage: 550mg tablet.

Special considerations or risks: Clostridium difficile infection has been reported with use of nearly all antibacterial agents. While data from preliminary studies concerning rates of C. difficile are reassuring, whether rates of C. difficile are increased with repeated courses of rifaximin remains unknown.

Most common side effects: Similar side effects to placebo.

Recommendation: ACG suggests rifaximin for overall IBS-D symptom improvement.