What are the clinical guidelines for managing Irritable Bowel Syndrome with Constipation (IBS-C)?

Clinical Guidelines for IBS-C Management

For IBS-C, begin with dietary modifications and lifestyle interventions, then escalate to FDA-approved secretagogues (linaclotide 290 mcg, plecanatide, lubiprostone, or tenapanor) if symptoms persist, and add tricyclic antidepressants for refractory abdominal pain. 1

Diagnosis and Initial Assessment

Make a positive diagnosis in patients under 45 years meeting Rome IV criteria (abdominal pain at least 1 day per week for 3 months, associated with altered bowel habits) without alarm features, avoiding extensive testing. 1

• Alarm features requiring investigation: New onset after age 50, rectal bleeding not from hemorrhoids/fissures, unintentional weight loss, iron deficiency anemia, nocturnal symptoms, family history of colon cancer/inflammatory bowel disease/celiac disease. 1
• Minimal testing recommended: Full blood count, C-reactive protein or ESR, celiac serology, and fecal calprotectin if age <45 years. 1

First-Line Management: Communication and Lifestyle

Provide clear explanation that IBS-C is a benign disorder of brain-gut interaction with a relapsing-remitting course, emphasizing that stress aggravates symptoms and treatments aim to improve quality of life rather than cure. 1

Dietary and Lifestyle Modifications

• Establish regular meal patterns with adequate time for defecation and regular exercise. 1
• Increase soluble fiber intake (ispaghula/psyllium 3-4 g/day) starting at low doses and titrating gradually; if symptoms worsen with bran, switch to ispaghula. 1
• Trial low FODMAP diet as second-line dietary therapy if symptoms persist, delivered only by healthcare professionals with dietary expertise, with planned reintroduction according to tolerance. 1, 2
• Reduce bloating triggers: Consider reducing intake of insoluble fiber, lactose, fructose, caffeine, and alcohol as relevant. 1, 2

Second-Line Pharmacological Treatment

FDA-Approved Secretagogues (Preferred)

Linaclotide 290 mcg once daily is the recommended first-line pharmacological agent for IBS-C, taken on an empty stomach at least 30 minutes before a meal. 1, 3

• Alternative secretagogues: Plecanatide, lubiprostone, or tenapanor are equally effective options based on patient preference, insurance coverage, and tolerability. 1, 4
• Review efficacy after 3 months and discontinue if no response. 1
• Common side effect: Diarrhea, which typically improves with continued use or dose reduction. 4

Osmotic Laxatives

Polyethylene glycol laxatives may be considered as an alternative or adjunct, though evidence is less robust than for secretagogues. 1

Third-Line Treatment for Refractory Abdominal Pain

Tricyclic Antidepressants (First Choice)

Start amitriptyline 10 mg at bedtime and titrate slowly (by 10 mg weekly) according to response and tolerability, continuing for at least 6 months if symptomatic improvement occurs. 1

• Caution: TCAs may worsen constipation; monitor bowel habits closely and adjust secretagogue dose if needed. 1
• Alternative: SSRIs may be considered if TCAs are not tolerated, though evidence is less robust. 1

Antispasmodics for Abdominal Pain

Anticholinergic agents (dicyclomine) or peppermint oil may provide symptomatic relief for abdominal pain in a limited proportion of patients. 1

Psychological Therapies for Refractory Symptoms

Refer for IBS-specific cognitive behavioral therapy (CBT) or gut-directed hypnotherapy when symptoms persist despite 12 months of pharmacological treatment, or earlier based on patient preference and local availability. 1

• Initial psychological approach: Simple relaxation therapy using audiotapes may be beneficial. 1
• Exclude overt psychiatric disease before hypnotherapy; refer for psychiatric evaluation if serious psychiatric comorbidity is present. 1

Treatment Algorithm Summary

1. Positive diagnosis with minimal testing in appropriate patients 1
2. Lifestyle and dietary modifications (regular meals, exercise, soluble fiber, consider low FODMAP) 1, 2
3. FDA-approved secretagogue (linaclotide 290 mcg preferred) if symptoms persist 1, 3
4. Add TCA (amitriptyline starting 10 mg) for refractory abdominal pain 1
5. Psychological therapy (CBT or gut-directed hypnotherapy) for symptoms persisting >12 months 1

Common Pitfalls to Avoid

• Avoid insoluble fiber (wheat bran) as it consistently exacerbates IBS symptoms. 1, 2
• Do not over-investigate patients meeting diagnostic criteria without alarm features, as this reinforces illness behavior and increases costs. 1
• Recognize cost barriers: Newer FDA-approved medications are brand-name only; prior authorization may be required, and the case is strengthened when generic therapies have failed. 1
• Address psychological factors early: Identify sleep disorders, mood disturbances, history of abuse, poor social support, and somatization, as these predict treatment failure if unaddressed. 1