What are the treatment options for outpatient management of Irritable Bowel Syndrome (IBS)?

Outpatient Management of Irritable Bowel Syndrome

The first-line treatment for irritable bowel syndrome (IBS) should be antispasmodics, with specific medications including hyoscine (Buscopan) 10mg up to three times daily or dicyclomine 10-20mg three to four times daily, based on the patient's predominant symptoms. 1

Pharmacological Treatment Algorithm Based on IBS Subtype

For All IBS Subtypes

• First-line: Antispasmodics for pain relief

  • Hyoscine 10mg up to three times daily
  • Dicyclomine 10-20mg three to four times daily
  • Consider adding simethicone for bloating

• Second-line: Low-dose tricyclic antidepressants (TCAs)

  • Amitriptyline starting at 10mg at bedtime (provides global symptom relief with RR 0.67; 95% CI 0.54-0.82) 1
  • For patients with concurrent mood disorders, consider SSRIs instead

• Third-line: Combination therapy

  • Antispasmodic + simethicone for pain and bloating
  • Neuromodulators (e.g., gabapentin) + antidepressants for severe pain

For IBS with Constipation (IBS-C)

1. Increase soluble fiber (ispaghula/psyllium) starting at 3-4g/day and gradually increasing 1
2. Consider lubiprostone, which is FDA-approved for IBS-C in women ≥18 years 2

For IBS with Diarrhea (IBS-D)

1. Antidiarrheals (loperamide) for symptom control
2. Consider rifaximin, which is FDA-approved for IBS-D in adults 3
3. For refractory cases, consider bile acid sequestrants 4

Dietary Management

• Low FODMAP Diet: Recommended for moderate to severe gastrointestinal symptoms

  • Effective for reducing bloating and pain (RR 0.51 [95% CI 0.37-0.70]) 1
  • Should be implemented under dietitian supervision
  • Requires at least 12 weeks trial period

• Mediterranean Diet: Recommended for patients with psychological-predominant symptoms 1

• Fiber Management:

  • Increase soluble fiber (ispaghula/psyllium) for IBS-C
  • Decrease fiber for IBS-D patients
  • Avoid insoluble fiber (wheat bran) as it may worsen symptoms 1

• Food Trigger Identification:

  • Identify and reduce excessive consumption of:
    • Lactose
    • Fructose
    • Sorbitol
    • Caffeine
    • Alcohol 1

Lifestyle Modifications

• Regular exercise despite weak evidence 1
• Establish a regular defecation schedule
• Peppermint oil daily for symptom relief 1
• Adequate hydration

Treatment Reassessment and Escalation

• Reassess treatment approach after 4-6 weeks
• Modify if no improvement is seen
• Discontinue ineffective treatments after 12 weeks 1

When to Refer to Specialists

Refer to Gastroenterology when:

• Diagnostic doubt exists
• Symptoms are severe or refractory to first-line treatments
• Patient requests specialist opinion 1

Refer to Dietitian when:

• Patient reports considerable intake of trigger foods
• Dietary deficits or nutrition red flags are present
• Food-related fear is pathological 1

Common Pitfalls to Avoid

• Excessive investigation and testing
• Continuing ineffective treatments beyond 12 weeks
• Using insoluble fiber (wheat bran)
• Overlooking psychological factors
• Using conventional analgesics or opioids, which may worsen symptoms 1
• Antibiotics unless there is evidence of superinfection (exception: rifaximin for IBS-D) 1, 3

Special Considerations

• An integrated care approach addressing both gastrointestinal symptoms and psychological aspects is considered the gold standard for IBS management 1
• Patient education about the benign but relapsing/remitting nature of IBS is essential 1
• Effectiveness of lubiprostone in patients taking diphenylheptane opioids (e.g., methadone) has not been established 2