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

Treatment for Irritable Bowel Syndrome (IBS)

Start all IBS patients on regular exercise and first-line dietary advice with soluble fiber, then escalate to antispasmodics for pain or loperamide for diarrhea, reserving low-dose tricyclic antidepressants (10-30 mg amitriptyline) as the most effective second-line treatment for refractory symptoms. 1, 2

Initial Management: Diagnosis and Patient Education

• Make a positive diagnosis in patients under 45 years meeting diagnostic criteria without alarm features (unintentional weight loss, blood in stool, fever, anemia, family history of colon cancer or inflammatory bowel disease) and avoid extensive testing. 1, 2
• Explain that IBS is a disorder of gut-brain interaction with a benign but relapsing/remitting course to establish realistic expectations. 1, 2
• Use a symptom diary to track triggers and involve patients actively in disease management. 1

First-Line Treatment: Universal for All Patients

Lifestyle Modifications

• Prescribe regular physical activity to all IBS patients, as exercise provides significant benefits for symptom management. 1, 2
• Establish regular time for defecation and ensure adequate sleep hygiene. 2

Dietary Interventions

• Start with soluble fiber (ispaghula/psyllium) at 3-4 g/day and gradually increase to avoid bloating—this is effective for global symptoms and abdominal pain. 3, 1, 2
• Avoid insoluble fiber (wheat bran) as it exacerbates symptoms, particularly bloating. 3, 2
• For diarrhea-predominant IBS (IBS-D), reduce fiber intake and identify excessive consumption of lactose (>280 ml milk/day), fructose, sorbitol, caffeine, or alcohol. 1, 2
• Food elimination diets based on IgG antibodies are not recommended. 3
• A gluten-free diet is not recommended in IBS. 3, 2

Probiotics

• Probiotics as a group may be effective for global symptoms and abdominal pain, but no specific species or strain can be recommended. 3, 1
• Advise a 12-week trial and discontinue if no improvement. 3, 1

Pharmacological Treatment: Symptom-Targeted Approach

For Abdominal Pain and Cramping

• Use antispasmodics with anticholinergic properties (dicyclomine) as first-line therapy for abdominal pain, particularly when symptoms are meal-related. 1, 2
• Hyoscyamine is FDA-approved as adjunctive therapy in IBS and can be used sublingually for rapid relief of unpredictable severe pain episodes. 4, 5
• Peppermint oil may be useful as an alternative antispasmodic, though evidence is more limited. 1, 2
• Common side effects include dry mouth, visual disturbance, and dizziness. 3

For Diarrhea-Predominant IBS (IBS-D)

• Prescribe loperamide 4-12 mg daily either regularly or prophylactically (before going out) to reduce stool frequency, urgency, and fecal soiling. 1, 2
• Titrate the dose carefully as abdominal pain, bloating, nausea, and constipation are common and may limit tolerability. 3, 2
• A morning dose before breakfast (2-6 mg) is typically used, with additional doses later in the day when diarrhea symptoms are prominent. 5

For Constipation-Predominant IBS (IBS-C)

• Increase dietary fiber or use soluble fiber supplements like ispaghula/psyllium as described above. 1, 2

Second-Line Treatment: Low FODMAP Diet

• For persistent symptoms refractory to first-line measures, consider a supervised trial of low FODMAP diet delivered in three phases: restriction, reintroduction, and personalization. 1, 2, 6
• This approach requires supervision by a trained dietitian to avoid nutritional deficits and ensure proper reintroduction according to tolerance. 3, 1, 6
• The low FODMAP diet has the most robust data for improving overall symptom burden among dietary interventions. 7

Second-Line Pharmacological Treatment: Neuromodulators

Tricyclic Antidepressants (TCAs)

• TCAs are the most effective first-line pharmacological treatment for global symptoms, abdominal pain, and mixed IBS symptoms refractory to first-line measures. 3, 1, 2
• Start with amitriptyline 10 mg once daily and titrate slowly to a maximum of 30-50 mg once daily. 3, 1, 2
• Provide careful explanation as to the rationale for their use (gut-brain neuromodulation, not depression treatment) and counsel about side-effect profile. 3, 1
• TCAs are especially effective in diarrhea-predominant patients with disturbed sleep patterns but may worsen constipation. 1, 5
• Continue for at least 6 months if the patient reports symptomatic improvement. 1

Selective Serotonin Reuptake Inhibitors (SSRIs)

• SSRIs may be effective for global symptoms and can be considered if TCAs are not tolerated or if there is concurrent mood disorder. 3, 1
• SSRIs may be more appropriate for constipation-predominant IBS. 5
• Warn patients that anxiety and disturbed sleep may occur during the first 10 days and benefits may not occur for 3-4 weeks. 5

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, 2, 6
• These brain-gut behavior therapies are specifically designed for IBS and differ from psychological therapies that target depression and anxiety alone. 1, 2, 6
• Refer to a gastropsychologist if IBS symptoms or their impact are moderate to severe, the patient accepts that symptoms are related to gut-brain dysregulation, and has time to devote to learning new coping strategies. 1, 2

Multidisciplinary Care Coordination

• Refer to a gastroenterology dietitian if the patient consumes considerable intake of foods that trigger IBS symptoms, shows dietary deficits or nutritional deficiency, shows recent unintended weight loss, or requests dietary modification advice. 1, 2
• Build collaborative links with gastroenterology dietitians and gastropsychologists to coordinate high-quality care. 1

Treatment Monitoring and Adjustment

• Review treatment efficacy after 3 months and discontinue ineffective medications. 1, 2
• Recognize that symptoms may relapse and remit over time, requiring periodic adjustment of treatment strategy. 1, 2

Important Caveats

• Avoid colonoscopy in IBS except in those with alarm symptoms or signs, or those with IBS-D who have atypical features (nocturnal or severe watery diarrhea, age ≥50 years, coexistent autoimmune disease, weight loss) that increase likelihood of microscopic colitis. 3
• In IBS-D with atypical features such as nocturnal diarrhea or prior cholecystectomy, consider testing for bile acid malabsorption. 3
• Promote patient empowerment through education using handouts, self-help books, websites, and apps targeting physical activity, sleep hygiene, mindful eating, and assertive communication. 1