What are the treatment options for a patient with Irritable Bowel Syndrome (IBS)?

Treatment of Irritable Bowel Syndrome

Begin with lifestyle modifications (regular exercise and dietary counseling), then escalate to symptom-targeted pharmacotherapy based on IBS subtype (diarrhea-predominant, constipation-predominant, or mixed), reserving neuromodulators for refractory abdominal pain and psychological therapies for persistent symptoms despite 12 months of medical management. 1, 2

Initial Management and Patient Education

• Establish a positive diagnosis in patients under 45 meeting Rome criteria without alarm features to avoid unnecessary testing. 3, 2
• Explain that IBS is a disorder of gut-brain interaction with a benign but relapsing/remitting course, directly addressing patient fears about cancer. 3, 2
• Consider using a symptom diary to identify triggers and guide treatment choices. 3, 2

First-Line Treatment: Lifestyle and Dietary Modifications

All patients should receive:

• Regular physical exercise as foundational therapy, which provides significant benefits for global symptom management. 1, 3, 2
• Initial dietary counseling focusing on adequate time for defecation, identifying excessive intake of lactose, fructose, sorbitol, or caffeine. 1, 3

For constipation-predominant symptoms:

• Start soluble fiber (ispaghula/psyllium) 3-4 g/day, building up gradually to avoid bloating and gas. 1, 3, 2
• Avoid insoluble fiber (wheat bran) as it consistently worsens symptoms. 1, 3

For moderate to severe symptoms not responding to initial measures:

• Consider a supervised trial of low FODMAP diet delivered in three phases (restriction, reintroduction, personalization) by a trained dietitian. 1, 3, 2
• Do not recommend gluten-free diets unless celiac disease has been confirmed. 1, 3

Probiotics:

• Trial for 12 weeks for global symptoms and abdominal pain; discontinue if no improvement. 1, 2

Pharmacological Treatment by IBS Subtype

IBS with Diarrhea (IBS-D)

First-line:

• Loperamide 2-4 mg up to four times daily (either regularly or prophylactically before going out) to reduce stool frequency, urgency, and fecal soiling. 1, 3, 2

Second-line:

• Rifaximin 550 mg three times daily for 14 days as a second-line agent, though its effect on abdominal pain is limited. 1, 3
• 5-HT3 receptor antagonists (ondansetron titrated from 4 mg once daily to maximum 8 mg three times daily) for refractory diarrhea. 1, 3

IBS with Constipation (IBS-C)

First-line:

• Increase dietary fiber or use soluble fiber supplements (ispaghula/psyllium) 3-4 g/day, gradually increased. 1, 3, 2
• Polyethylene glycol (osmotic laxative) for persistent constipation, titrating the dose according to symptoms. 1, 3

Second-line:

• Linaclotide 290 mcg once daily on an empty stomach is the most effective secretagogue and should be the preferred second-line agent when first-line therapies fail. 1, 3
• Lubiprostone 8 mcg twice daily with food is an alternative if linaclotide is not tolerated, though nausea is the most common side effect (19% vs 14% placebo). 1, 3, 4

Critical caveat for IBS-C:

• Avoid anticholinergic antispasmodics (like dicyclomine) in IBS-C as they reduce intestinal motility and enhance water reabsorption, which will worsen constipation. 1

For severe refractory constipation:

• Add bisacodyl 10-15 mg once daily, increasing to twice or three times daily if needed after 2-4 weeks. 1

IBS with Mixed Symptoms (IBS-M)

First-line:

• Tricyclic antidepressants (TCAs) are the most effective first-line pharmacological treatment for mixed IBS, starting with amitriptyline 10 mg once daily and gradually titrating to 30-50 mg once daily. 5, 1, 2

Treatment of Abdominal Pain (All Subtypes)

First-line:

• Antispasmodics with anticholinergic properties (dicyclomine) for abdominal pain, particularly when symptoms are meal-related. 3, 2
• Peppermint oil may be useful as an alternative antispasmodic. 1, 3

Second-line (for refractory pain):

• Tricyclic antidepressants (TCAs) should be the first choice for abdominal pain, initiated at low doses (amitriptyline 10 mg once daily) and titrated according to symptomatic response to maximum 30-50 mg once daily. 5, 1, 3, 2
• Start at bedtime and explain the rationale clearly, as these are used for pain modulation via gut-brain interaction, not for depression. 3
• Continue for at least 6 months if the patient reports symptomatic improvement. 1, 3
• TCAs can cause constipation by prolonging whole-gut transit time, which might be helpful in diarrhea-predominant IBS but problematic in IBS-C. 5, 1

Alternative neuromodulators:

• SSRIs offer an alternative option if symptoms do not respond to TCAs or if TCAs worsen constipation. 5, 1, 3
• If a mood disorder is suspected, then an SSRI at a therapeutic dose might be a better initial choice than low-dose TCAs because low doses of TCAs are unlikely to be adequate to treat a mood disorder. 5, 2

Psychological Therapies

Indications:

• Consider when symptoms persist despite pharmacological treatment for 12 months. 1, 3, 2
• Particularly recommended for patients who relate symptom exacerbations to stressors, have associated anxiety or depression, or have symptoms of relatively short duration. 3

Recommended therapies:

• IBS-specific cognitive behavioral therapy is effective for global symptoms. 1, 3, 2
• Gut-directed hypnotherapy is effective for global symptoms. 1, 3, 2
• Dynamic (interpersonal) psychotherapy for patients who relate symptom exacerbations to stressors. 3

Treatment Monitoring and Adjustment

• Review treatment efficacy after 3 months and discontinue ineffective medications. 1, 3, 2
• Recognize that symptoms may relapse and remit over time, requiring periodic adjustment of treatment strategy. 3, 2
• Manage expectations realistically, as complete symptom resolution is often not achievable; the goal is symptom relief and improved quality of life. 3

Critical Pitfalls to Avoid

• Avoid extensive testing once IBS diagnosis is established in patients under 45 without alarm features. 3, 2
• Do not recommend IgG antibody-based food elimination diets, as they lack evidence and may lead to unnecessary dietary restrictions. 1, 3
• Avoid opioids for chronic abdominal pain management due to risks of dependence and complications. 5, 3
• Do not prescribe anticholinergic antispasmodics like dicyclomine for IBS-C based solely on the "IBS" diagnosis without considering the constipation subtype, which can worsen the constipation. 1
• Discontinue docusate (stool softener) immediately as it lacks efficacy for constipation. 1

Multidisciplinary Approach for Refractory Cases

• Build collaborative links with gastroenterology dietitians for patients reporting considerable intake of trigger foods or having dietary deficits. 2
• Refer to gastropsychologists if IBS symptoms are moderate to severe and the patient accepts that symptoms are related to gut-brain dysregulation. 2
• Promote patient empowerment through education targeting physical activity, sleep hygiene, mindful eating, and assertive communication. 2