What is the best treatment for a patient with chronic abdominal pain and functional abdominal pain?

Treatment of Chronic Functional Abdominal Pain

Start low-dose tricyclic antidepressants (amitriptyline 10 mg at bedtime, titrating to 30-50 mg daily) as first-line pharmacotherapy for chronic functional abdominal pain, combined with cognitive behavioral therapy or gut-directed hypnotherapy. 1, 2

Pharmacologic Management

First-Line: Tricyclic Antidepressants

• Initiate amitriptyline 10 mg once daily at bedtime, increasing slowly to 30-50 mg daily based on response. 1, 2 TCAs work as "gut-brain neuromodulators" with analgesic properties independent of mood effects, modulating pain processing in the brain and spinal cord. 3, 1
• Analgesic effects occur at lower doses than required for mood effects, typically within 1-3 weeks (though adverse effects appear within days). 3, 1
• TCAs are superior to SSRIs for abdominal pain based on meta-analysis data. 1

Second-Line: SNRIs

• If TCAs are not tolerated, switch to duloxetine (serotonin-norepinephrine reuptake inhibitor) for pain relief through descending pain modulation pathways. 3, 4
• SNRIs require 2-4 weeks for efficacy and are particularly useful for patients with more severe symptoms. 3

Symptom-Specific Adjuncts

• For meal-related pain exacerbations, add antispasmodics (dicyclomine 40 mg four times daily or hyoscyamine). 2, 5, 6 Dicyclomine demonstrated 82% favorable response versus 55% with placebo in controlled trials. 5
• For diarrhea-predominant symptoms, loperamide 2-4 mg up to four times daily reduces loose stools and urgency. 2
• For constipation-predominant symptoms, increase dietary fiber to 25 g/day, though evidence for pain reduction is mixed. 2

Critical Medication Avoidance

• Never prescribe opioids for chronic functional abdominal pain. 3, 1, 2 Opioids cause narcotic bowel syndrome (occurring in ~6% of chronic users), dependence, gut dysmotility, serious infection risk, and increased mortality. 1
• Avoid benzodiazepines due to high risk of dependence and potential to worsen symptoms long-term. 2, 7

Psychological Interventions

Brain-Gut Behavior Therapies (Initiate Early)

• Refer to a psychologist experienced in chronic pain for cognitive behavioral therapy (CBT) or gut-directed hypnotherapy. 3, 1, 2 These therapies target cognitive-affective factors that amplify pain, including pain catastrophizing. 3
• CBT is most effective for patients with insight into how thoughts, feelings, and behaviors relate to their pain. 1
• Gut-directed hypnotherapy and mindfulness-based stress reduction have strong evidence for global symptom improvement. 3, 2
• Initiate psychological treatments when symptoms impair quality of life, not after 12 months of failed medical therapy. 2

Immediate Self-Management Strategies

• Teach breathing techniques and relaxation training immediately (can be taught by the gastroenterologist) to address heightened autonomic arousal related to pain and stress. 3, 1
• Encourage regular exercise to offset negative consequences of pain-related inactivity, improving physical function and quality of life. 3, 1

Dietary Approaches

• Provide standard dietary advice for mild gastrointestinal symptoms. 2
• For moderate-to-severe symptoms, refer to a specialized gastroenterology dietitian for supervised low FODMAP diet. 1, 2
• Consider Mediterranean diet for patients with psychological-predominant symptoms. 1

Communication Strategy

• Establish a collaborative, empathic relationship acknowledging that pain is real and multifactorial. 4, 2 Explain that the brain's pain processing system requires treatment using a gut-brain axis framework, not that pain is "all in their head." 4
• Validate that both gastrointestinal and psychological symptoms are real and taken seriously. 1
• Avoid language suggesting the patient "shouldn't be in so much pain" or continuing to order tests to find the "cause." 1 This reinforces pain catastrophizing.
• Set realistic expectations: substantial improvement in symptoms and quality of life is achievable, but cure is unlikely. 4

Diagnostic Considerations

• Complete basic laboratory workup (CBC, liver function tests, inflammatory markers) to exclude organic pathology, then stop further invasive testing once functional diagnosis is established. 4, 8
• Avoid repetitive testing after functional diagnosis is confirmed, as this increases costs without benefit and reinforces illness behavior. 1, 8
• Screen explicitly for trauma, early-life adversity, and poor social support, as these are established risk factors that predict worse outcomes. 1

Escalation for Refractory Cases

• Refer to a gastropsychologist or psychiatrist if moderate-to-severe depression, suicidal ideation, low social support, impaired quality of life, or avoidance behavior is present. 1
• Consider combination neuromodulators (e.g., duloxetine plus gabapentin) for severe refractory symptoms, but monitor vigilantly for serotonin syndrome (fever, hyperreflexia, tremor, sweating, diarrhea). 4, 2
• For severe and refractory symptoms, refer to a multidisciplinary pain center. 2

Monitoring

• Reevaluate after 3-6 weeks of initial treatment. 2
• Adjust visit duration and frequency to accommodate mental health needs and ongoing monitoring. 1
• Screen for untreated mood disorders at every visit, as these adversely affect treatment response. 2, 7