What are the treatment options for a patient with irritable bowel syndrome with constipation (IBS-C)?

Treatment of Irritable Bowel Syndrome with Constipation (IBS-C)

Start with soluble fiber supplementation (ispaghula/psyllium) at 3-4 g/day and gradually increase, avoiding insoluble fiber like wheat bran which worsens symptoms. 1, 2

Initial Management: Lifestyle and Dietary Interventions

Lifestyle Modifications

• Prescribe regular physical activity to all IBS-C patients, as exercise provides significant benefits for symptom management 1, 2
• Establish regular time for defecation and ensure adequate sleep hygiene 2
• Maintain a balanced diet with appropriate fiber intake 3, 1

Fiber Therapy (First-Line Treatment)

• Begin with soluble fiber (ispaghula/psyllium) starting at low doses (3-4 g/day) and gradually increase to minimize bloating and abdominal discomfort 1, 2, 4
• Avoid insoluble fiber (wheat bran) as it may exacerbate symptoms, particularly bloating 2, 4
• Give an adequate trial period and evaluate results early and periodically 4

Low FODMAP Diet

• Refer to a trained dietitian for a supervised trial of low FODMAP diet delivered in three phases: restriction, reintroduction, and personalization for patients with moderate to severe symptoms 1, 2
• This approach is particularly effective but requires professional guidance to avoid nutritional deficits 1

Pharmacological Treatment Algorithm

First-Line Pharmacological Options

For patients with inadequate response to fiber and lifestyle modifications, use FDA-approved secretagogues:

• Lubiprostone 8 mcg twice daily with food and water for women ≥18 years old with IBS-C 5, 6, 7

  • Take with food to reduce nausea 5
  • Monitor for diarrhea, syncope, and hypotension, especially after first dose 5
  • Adjust to 8 mcg once daily in severe hepatic impairment (Child-Pugh Class C) 5

• Linaclotide (guanylate cyclase-C agonist) is FDA-approved for IBS-C in adults 8, 6, 7

  • Generally well tolerated and efficacious in improving both constipation and abdominal pain 7

For Abdominal Pain Management

• Use antispasmodics with anticholinergic properties (dicyclomine) as first-line therapy for abdominal pain, particularly when symptoms are meal-related 3, 1, 2
• Peppermint oil may be useful as an alternative antispasmodic, though evidence is more limited 1, 2

Second-Line: Neuromodulators

For patients with refractory pain or mixed symptoms despite first-line therapies:

• Prescribe tricyclic antidepressants (TCAs) starting with amitriptyline 10 mg once daily at bedtime, titrating slowly to 30-50 mg once daily 3, 1, 6
• TCAs are particularly effective when insomnia is prominent 3, 1
• Warning: TCAs may aggravate constipation, so use cautiously in IBS-C 3, 1
• Continue for at least 6 months if patient reports symptomatic improvement 1
• If concurrent mood disorder exists, use selective serotonin reuptake inhibitors (SSRIs) instead of low-dose TCAs 1

Probiotics

• Trial probiotics for 12 weeks for global symptoms and bloating; discontinue if no improvement 1, 2

Psychological Therapies for Refractory Cases

When symptoms persist despite pharmacological treatment for 12 months:

• Initially offer explanation, reassurance, and simple relaxation therapy using audiotapes 3, 1
• Consider IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy for symptoms refractory to pharmacological treatment 1, 2, 6
• These brain-gut behavior therapies are specifically designed for IBS and differ from psychological therapies targeting depression and anxiety alone 1
• Biofeedback may be especially helpful for disordered defecation 3, 1

Treatment Monitoring and Follow-Up

• Review treatment efficacy after 3 months and discontinue ineffective medications 1, 2
• Periodically assess the need for continued therapy, recognizing that symptoms may relapse and remit over time 1, 5

Critical Pitfalls to Avoid

• Do not pursue extensive testing once IBS-C diagnosis is established 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) 1, 2
• Avoid insoluble fiber (wheat bran) as it worsens symptoms 2, 4
• Do not recommend IgG-based food allergy testing, as true food allergy is rare in IBS 2
• Avoid osmotic laxatives for overall IBS symptoms as they are not recommended 6

Multidisciplinary Referral Criteria

• Refer to gastroenterology dietitian if patient consumes considerable intake of foods that trigger IBS symptoms, or has dietary deficits or nutrition red flags 1, 2
• Refer to gastropsychologist if IBS symptoms or their impact are moderate to severe, patient accepts that symptoms are related to gut-brain dysregulation, and has time to devote to learning new coping strategies 1