Soluble Fiber (Psyllium, Ispaghula Husk)

How it works: Poorly fermented, soluble, gel-forming fiber softens stool and increases fecal biomass, which could benefit bowel symptoms in patients with IBS-C or chronic constipation.

Which symptoms does it help: Stool frequency, stool consistency, and straining are most likely to improve.

How long it takes to see a benefit: Varies from days to weeks.

FDA approved: Over the counter (no prescription needed).

Dosage: Dose titration typically required. Start at a low dose and slowly increase over days to weeks.

Special considerations or risks: N/A

Most common side effects: Bloating, distention, flatulence, cramping.

Recommendation: ACG recommends psyllium, but not wheat bran, for overall symptom improvement in IBS patients.