What is the initial approach to managing irritable bowel syndrome (IBS)?

Initial Approach to Irritable Bowel Syndrome Workup

For 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), make a confident positive diagnosis without extensive testing. 1, 2

Diagnostic Approach

Make the Positive Diagnosis

• Establish IBS diagnosis clinically in patients <45 years meeting three or more Rome criteria without sinister symptoms—extensive testing is unnecessary and reinforces abnormal illness behavior. 3
• Avoid ordering extensive investigations once diagnosis is established, as this increases costs and patient anxiety without improving outcomes. 2
• Consider serological testing only to exclude celiac disease; do not routinely test for C-reactive protein, fecal calprotectin, or IgG-based food allergies. 4

Initial Patient Encounter Structure

• Listen to the patient's specific concerns and identify their beliefs about the condition—many patients fear cancer or serious disease. 3
• Determine why the patient is seeking help now (cancer phobia, disability concerns, interpersonal distress, or symptom exacerbation). 5
• Have the patient keep a 2-week diary tracking food intake and gastrointestinal symptoms to identify triggers and engage them actively in management. 3, 5

Patient Education and Reassurance

Explain the Condition

• Describe IBS as a disorder of gut-brain interaction with a benign prognosis and relapsing/remitting course. 3, 1
• Explain the concept of a sensitive or hyperactive gut that responds to stress, food, and other triggers. 3
• Clarify that stress may aggravate symptoms or worsen worry about the condition, impairing coping abilities. 3
• Note that some cases are precipitated by bacterial gastroenteritis. 3

First-Line Management: Lifestyle and Dietary Modifications

Lifestyle Interventions

• Recommend regular physical activity to all patients, as exercise provides significant benefits for symptom management. 1, 6
• Advise a balanced diet with adequate fiber intake, regular time for defecation, and proper sleep hygiene. 1, 2

Dietary Approach (Stepwise)

1. Establish the patient's habitual fiber intake first. 3, 2
2. For constipation-predominant IBS (IBS-C): Start soluble fiber supplementation (ispaghula/psyllium) at low doses (3-4 g/day) and gradually increase. 1, 2, 7
3. Avoid insoluble fiber (wheat bran) as it may worsen symptoms, particularly bloating. 1, 8
4. For diarrhea-predominant IBS (IBS-D): Identify and reduce excessive intake of lactose, fructose, sorbitol, caffeine, or alcohol. 3, 2
5. Consider a supervised trial of low FODMAP diet delivered in three phases (restriction, reintroduction, personalization) by a trained dietitian for persistent symptoms. 1, 4
6. Reassure that true food allergy is rare but food intolerance (such as to bran) is common. 3

Psychological Assessment

Screen for Psychological Comorbidities

• Identify features of psychological disorders: sleep disturbances, mood disorders, previous psychiatric disease. 3
• Ask about history of current or past physical/sexual abuse. 3
• Assess for poor social support or adverse social factors (separation, bereavement). 3
• Identify somatization patterns: multiple somatic complaints, frequent doctor visits. 3

Initial Psychological Interventions

• Begin with explanation, reassurance, and simple relaxation therapy using audiotapes. 3, 2
• For symptoms refractory to pharmacological treatment for 12 months, consider IBS-specific cognitive behavioral therapy or gut-directed hypnotherapy. 1, 2

Symptom-Directed Pharmacological Treatment

For Abdominal Pain and Cramping

• Use antispasmodics (anticholinergic agents like dicyclomine) as first-line therapy, particularly when symptoms are meal-related. 1, 2
• Consider peppermint oil as an alternative antispasmodic, though evidence is more limited. 1, 4

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. 3, 1, 2
• Encourage patients to use divided doses and make decisions about timing—typically a morning dose before breakfast (2-6 mg) and possibly again later when symptoms are prominent. 5
• Codeine 30-60 mg, 1-3 times daily can be tried but central nervous system effects are often unacceptable. 3, 2

For Constipation-Predominant IBS (IBS-C)

• Increase dietary fiber (soluble fiber like ispaghula/psyllium); if symptoms worsen, adjust the type or dose. 3, 2

For Bloating

• Try reducing intake of fiber, lactose, or fructose as relevant. 3, 2
• Trial probiotics for 12 weeks for global symptoms and bloating; discontinue if no improvement. 1

For Mixed IBS or Refractory Pain

• Use tricyclic antidepressants (amitriptyline/trimipramine) starting at 10 mg once daily and titrating to 30-50 mg once daily, especially when insomnia is prominent. 1, 2
• Note that tricyclics may aggravate constipation. 3, 2
• Consider selective serotonin reuptake inhibitors if tricyclics are not tolerated. 2

Treatment Monitoring and Follow-Up

• Review treatment efficacy after 3 months and discontinue ineffective medications. 2
• Continue tricyclic antidepressants for at least 6 months if the patient reports symptomatic improvement. 2
• Recognize that symptoms may relapse and remit over time, requiring periodic adjustment of treatment strategy. 2

Critical Pitfalls to Avoid

• Do not pursue extensive testing once IBS diagnosis is established in patients under 45 without alarm features. 1
• Avoid recommending IgG-based food allergy testing, as true food allergy is rare in IBS. 1
• Do not use excessive fiber supplementation, as abdominal cramps and bloating may worsen. 5, 8
• Avoid long-term opioid use due to risk of addiction and potential worsening of IBS symptoms (narcotic bowel syndrome). 6
• Do not implement restrictive diets without proper dietitian supervision, which can lead to nutritional deficiencies. 6