What are the treatment options for irritable bowel syndrome (IBS)?

Treatment of Irritable Bowel Syndrome

Start with lifestyle modifications and dietary interventions for all IBS patients, then add symptom-specific pharmacotherapy based on whether the patient has diarrhea-predominant (IBS-D), constipation-predominant (IBS-C), or mixed symptoms, reserving psychological therapies and antidepressants for refractory cases. 1

Initial Approach: Diagnosis and Patient Education

Make a positive diagnosis in patients under 45 years meeting diagnostic criteria without alarm features (unintentional weight loss ≥5%, blood in stool, fever, anemia, family history of colon cancer or inflammatory bowel disease), and avoid extensive testing. 1, 2

• Explain to patients that IBS is a disorder of gut-brain interaction with a benign but relapsing/remitting course to establish realistic expectations and reduce anxiety. 1, 2
• Listen to patient concerns, identify their beliefs about the condition, and address fears directly rather than ordering extensive testing once diagnosis is established. 1, 2
• Consider using a symptom diary to track triggers and patterns. 1

First-Line Treatment: Lifestyle and Dietary Modifications

Lifestyle Changes

Recommend regular physical activity to all IBS patients, as exercise provides significant benefits for symptom management. 1, 3, 2

Dietary Interventions

For IBS-C: Start with soluble fiber supplementation (ispaghula/psyllium) at low doses (3-4 g/day) and gradually increase to avoid bloating. 1, 3, 2

For IBS-D: Identify and reduce excessive intake of lactose, fructose, sorbitol, caffeine, or alcohol. 1, 3

Avoid insoluble fiber (wheat bran) as it may worsen symptoms, particularly bloating. 2

For persistent symptoms despite initial dietary changes: Consider a trial of low FODMAP diet under supervision of a trained dietitian, delivered in three phases: restriction, reintroduction, and personalization. 1, 3, 2

Symptom-Specific Pharmacotherapy

For Abdominal Pain and Cramping

Use antispasmodics with anticholinergic properties (like dicyclomine) as first-line therapy for abdominal pain, particularly when symptoms are meal-related. 1, 3, 2

• Peppermint oil may be useful as an alternative antispasmodic, though evidence is more limited. 1, 2

For Diarrhea-Predominant IBS (IBS-D)

Loperamide 4-12 mg daily (either regularly or prophylactically before going out) is the most effective first-line treatment for IBS-D, significantly reducing stool frequency, urgency, and fecal soiling. 1, 3, 2

• Codeine (15-30 mg, 1-3 times daily) is effective for diarrhea but more likely to cause sedation and dependency. 1, 3
• Cholestyramine may benefit approximately 10% of IBS-D patients with bile salt malabsorption, particularly those with <5% retention on SeHCAT testing, but is often less well tolerated than loperamide. 1, 3
• Rifaximin is FDA-approved for treatment of IBS-D in adults. 4
• Alosetron is FDA-approved for severe IBS-D in women, but carries boxed warnings for ischemic colitis (0.2% through 3 months) and complications of constipation (29% constipation rate at 1 mg twice daily). 5

For Constipation-Predominant IBS (IBS-C)

Increase dietary fiber or use soluble fiber supplements like ispaghula/psyllium, starting with low doses (3-4 g/day) and gradually increasing. 1, 2

For Bloating

• Try reducing intake of fiber, lactose, or fructose as relevant. 1
• Probiotics may improve global symptoms and bloating; recommend a 12-week trial and discontinue if no improvement. 1, 3, 2

Second-Line Treatments for Refractory Symptoms

Tricyclic Antidepressants (TCAs)

For IBS-M (mixed symptoms) or refractory pain: Tricyclic antidepressants (like amitriptyline) are the most effective first-line pharmacological treatment, particularly when insomnia is prominent. 1, 3, 2

• Start at low doses (10 mg once daily) and increase slowly to maximum 30-50 mg once daily. 1
• Continue for at least 6 months if the patient reports symptomatic improvement. 1
• Caution: TCAs may aggravate constipation. 1

Selective Serotonin Reuptake Inhibitors (SSRIs)

• Consider SSRIs if TCAs are not tolerated. 1, 3

Psychological Therapies for Refractory Cases

Consider IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy when symptoms persist despite pharmacological treatment for 12 months. 1, 3, 2

• Initially offer explanation, reassurance, and simple relaxation therapy. 1
• Biofeedback may be especially helpful for disordered defecation. 1

Treatment Monitoring and Adjustment

Review treatment efficacy after 3 months and discontinue ineffective medications. 1, 3

• Recognize that symptoms may relapse and remit over time, requiring periodic adjustment of treatment strategy. 1, 3
• TCAs should be continued for at least 6 months if the patient reports symptomatic improvement. 1

Critical Pitfalls to Avoid

Do not pursue extensive testing once IBS diagnosis is established in patients under 45 without alarm features. 1, 2

• Avoid IgG-based food allergy testing, as true food allergy is rare in IBS. 2
• Do not use osmotic laxatives for overall IBS symptoms. 6
• For alosetron users: Discontinue immediately if signs of ischemic colitis develop (rectal bleeding, bloody diarrhea, or new/worsening abdominal pain) and do not resume treatment. 5