What is the treatment for cyclic vomiting syndrome?

Treatment of Cyclic Vomiting Syndrome

The American Gastroenterological Association recommends amitriptyline 25-150 mg nightly as first-line prophylactic therapy for moderate-severe CVS (≥4 episodes/year lasting >2 days), combined with sumatriptan 20 mg intranasal plus ondansetron 8 mg sublingual as abortive therapy during the prodromal phase. 1

Disease Severity Classification Determines Treatment Intensity

Treatment strategy depends on classifying CVS severity:

• Mild CVS (<4 episodes/year, each lasting <2 days, no ED visits): Requires only abortive therapy 1
• Moderate-severe CVS (≥4 episodes/year, lasting >2 days, requiring ED visits): Requires both prophylactic and abortive therapy 1, 2

Phase-Specific Treatment Approach

Inter-Episodic Phase: Prophylactic Therapy

First-line prophylaxis:

• Start amitriptyline 25 mg at bedtime, titrate to goal dose of 1-1.5 mg/kg (typically 75-150 mg nightly) 1
• Obtain baseline ECG due to QTc prolongation risk 1
• Response rate is 67-75% 1, 2

Second-line prophylactic options when amitriptyline fails or is not tolerated:

• Topiramate: Start 25 mg daily, titrate to 100-150 mg daily in divided doses; monitor electrolytes and renal function twice yearly 1
• Levetiracetam: Start 500 mg twice daily, titrate to 1000-2000 mg daily in divided doses; monitor CBC 1
• Zonisamide: Start 100 mg daily, titrate to 200-400 mg daily; monitor electrolytes and renal function twice yearly 1

Adjunctive prophylaxis:

• Aprepitant (neurokinin-1 antagonist): 80 mg 2-3 times weekly for patients 40-60 kg, or 125 mg 2-3 times weekly for patients >60 kg 1

Essential lifestyle modifications for all patients:

• Maintain regular sleep schedule 1
• Avoid prolonged fasting 1
• Identify and avoid individual triggers 1
• Implement stress management techniques 1

Prodromal Phase: Abortive Therapy

The probability of successfully aborting an episode is highest when medications are taken immediately at onset of prodromal symptoms. 1

Standard abortive regimen:

• Sumatriptan 20 mg intranasal (can repeat once after 2 hours, maximum 2 doses per 24 hours) 1
  • Administer in head-forward position to optimize medication contact with anterior nasal receptors 1
  • Subcutaneous injection is an alternative for patients who cannot tolerate intranasal administration 1
• Ondansetron 8 mg sublingual (can repeat every 4-6 hours during episode) 1

Additional abortive agents to consider:

• Promethazine 12.5-25 mg oral/rectal every 4-6 hours 1
• Prochlorperazine 5-10 mg every 6-8 hours or 25 mg suppository every 12 hours 1
• Sedatives (alprazolam, lorazepam, diphenhydramine) to truncate the episode, though use caution in patients with substance abuse risk 1

Emetic Phase: Emergency Department Management

When home abortive therapy fails, ED intervention includes:

• Aggressive IV fluid replacement with dextrose-containing fluids for rehydration and metabolic support 1
• Electrolyte replacement 1
• Ondansetron 8 mg IV every 4-6 hours 1
• Ketorolac IV as first-line non-narcotic analgesia for severe abdominal pain 1
• Sedation with benzodiazepines IV in a quiet, dark room 1
• Droperidol or haloperidol for refractory cases 1

Recovery Phase

• Focus on rehydration with electrolyte-rich fluids (sports drinks) 1
• Gradual introduction of nutrient drinks as tolerated 1
• Small, frequent sips as tolerated 1

Critical Diagnostic Consideration Before Treatment

Screen all patients for cannabis use before diagnosing CVS: Cannabis use >4 times weekly for >1 year suggests cannabinoid hyperemesis syndrome rather than CVS. 1, 2 However, hot water bathing for symptom relief occurs in 48% of non-cannabis users with CVS and is not pathognomonic for cannabinoid hyperemesis syndrome. 2

Management of Comorbid Conditions

• Screen for anxiety, depression, and panic disorder, as psychiatric comorbidities are present in 50-60% of CVS patients 1, 2
• Treating underlying anxiety can decrease CVS episode frequency 1
• Personal or family history of migraine (present in 20-30% of patients) supports CVS diagnosis and may guide treatment selection 1

Common Pitfalls to Avoid

• Missing the prodromal window dramatically reduces abortive therapy effectiveness 1, 2
• Overlooking retching and nausea leads to inadequate treatment, as these symptoms are equally disabling as vomiting 1
• Inadequate sedation during acute episodes can worsen symptoms 2
• Failing to recognize the stereotypical pattern of episodes delays diagnosis 2

When Standard Treatment Fails

For refractory patients despite optimized amitriptyline and abortive therapy:

• Consider higher doses of amitriptyline with careful monitoring 3
• Trial alternative prophylactic agents (topiramate, levetiracetam, zonisamide) 1
• Reconsider possible missed diagnoses 3
• Address comorbid anxiety and depression more aggressively 1
• Consider cognitive-behavioral therapy for psychological triggers 2