Treatment of Diarrhea-Predominant Irritable Bowel Syndrome

First-Line Treatments

The American Gastroenterological Association recommends loperamide at doses of 4-12 mg daily as the most effective first-line treatment for IBS-D, significantly reducing stool frequency and urgency 1, 2
Regular exercise should be recommended to all IBS-D patients as it provides significant benefits for symptom management 3
The National Institute for Health and Care Excellence provides clear dietary advice, including identification and reduction of excessive intake of lactose, fructose, sorbitol, caffeine, or alcohol in patients with diarrhea 2
A trial of low FODMAP diet under supervision of a trained dietitian may be considered for patients with persistent symptoms, with moderate strength of evidence 4
Soluble fiber (ispaghula/psyllium) may be beneficial, starting with low doses (3-4g/day) and gradually increasing to avoid bloating, with low strength of evidence 4

Loperamide at doses of 4-12 mg daily effectively slows intestinal transit and reduces stool frequency and urgency, with high strength of evidence 1
Codeine (15-30 mg, 1-3 times daily) is effective for diarrhea but more likely to cause sedation and dependency, with moderate strength of evidence 1

Antispasmodics with anticholinergic properties (like dicyclomine) show greater efficacy for pain relief compared to direct smooth muscle relaxants, with moderate strength of evidence 1
Tricyclic antidepressants (TCAs) are effective for pain and global symptoms in IBS-D, with high strength of evidence 1, 3
Selective serotonin reuptake inhibitors (SSRIs) may be considered if TCAs are not tolerated, with low strength of evidence 3

Approximately 10% of IBS-D patients show evidence of bile salt malabsorption and may respond to cholestyramine, particularly those with <5% retention on SeHCAT testing, with moderate strength of evidence 1
Probiotics may improve global symptoms and abdominal pain; recommend a 12-week trial and discontinue if no improvement, with low strength of evidence 4

Consider IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy for patients with symptoms refractory to pharmacological treatment for 12 months, with moderate strength of evidence 3
Simple relaxation therapy may be beneficial as an initial approach, with low strength of evidence 4

Review treatment efficacy after 3 months and discontinue ineffective medications, with high strength of evidence 4
Avoid extensive testing once IBS-D diagnosis is established, with moderate strength of evidence 4
Recognize that IBS is a disorder of gut-brain interaction requiring explanation of the gut-brain axis to patients, with high strength of evidence 3
Acknowledge that symptoms may relapse and remit over time, requiring periodic adjustment of treatment strategy, with moderate strength of evidence 2