What is the treatment for cyclic vomiting syndrome?

Treatment of Cyclic Vomiting Syndrome

For moderate-severe CVS (≥4 episodes/year lasting >2 days), start amitriptyline 25 mg at bedtime as prophylaxis and use combination sumatriptan 20 mg intranasal plus ondansetron 8 mg sublingual as abortive therapy during the prodromal phase. 1

Disease Severity Classification Determines Treatment Intensity

The first step is classifying disease severity, which directly dictates your treatment approach 1:

• Mild CVS: <4 episodes/year, each lasting <2 days, no ED visits or hospitalizations → requires only abortive therapy 2, 1
• Moderate-severe CVS: ≥4 episodes/year, lasting >2 days, requiring ED visits or hospitalizations → requires both prophylactic AND abortive therapy 2, 1

Prophylactic Therapy (Inter-episodic Phase)

Amitriptyline is the first-line prophylactic agent with a 67-75% response rate. 1, 3

Dosing Strategy:

• Start with 25 mg at bedtime 1
• Titrate up to goal dose of 75-150 mg nightly (1-1.5 mg/kg) 1
• Obtain baseline ECG due to QTc prolongation risk 1

Second-Line Prophylactic Options (if 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

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

Abortive Therapy (Prodromal Phase)

The highest probability of aborting an episode occurs when medications are taken immediately at the onset of prodromal symptoms. 1, 3 Missing this window dramatically reduces effectiveness 4.

Standard Abortive Regimen:

• Sumatriptan 20 mg intranasal (can repeat once after 2 hours, maximum 2 doses per 24 hours) 1
• Ondansetron 8 mg sublingual (can repeat every 4-6 hours during episode) 1
• Administer sumatriptan in head-forward position to optimize nasal receptor contact 1

Additional Abortive Agents ("Abortive Cocktail"):

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 (to truncate episodes): Alprazolam, lorazepam, or diphenhydramine; use caution in adolescents with substance abuse risk 1

Emergency Department Management (Emetic Phase)

When home abortive therapy fails, aggressive ED intervention is required 1:

Immediate ED Protocol:

• IV dextrose-containing fluids for rehydration and metabolic support 1, 3
• IV ondansetron 8 mg every 4-6 hours 1
• IV ketorolac as first-line non-narcotic analgesia for severe abdominal pain 1
• IV benzodiazepines for sedation in a quiet, dark room 1, 3
• Droperidol or haloperidol for refractory cases 1, 3

Recovery Phase Management

Focus on gradual reintroduction of fluids and nutrition 3:

• Rehydration with electrolyte-rich fluids (sports drinks) 3
• Small, frequent sips as tolerated 3
• Gradual introduction of nutrient drinks 3

Essential Lifestyle Modifications (All Patients)

These are non-negotiable components of management 1, 4:

• Maintain regular sleep schedule 1, 4
• Avoid prolonged fasting 1, 4
• Identify and avoid individual triggers (stress, infections, menstruation, travel, motion sickness) 2
• Implement stress management techniques 1, 4

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 (CHS) rather than CVS 1, 4. Hot water bathing is NOT pathognomonic for CHS—48% of CVS patients who don't use cannabis also find relief from hot bathing 2, 3.

Management of Comorbid Conditions

Treat underlying psychiatric comorbidities aggressively, as they are present in 50-60% of CVS patients. 2, 3

• Anxiety, depression, and panic disorder are the most common comorbidities 2, 3
• Treating anxiety can decrease CVS episode frequency and improve inter-episodic nausea 2, 3
• Migraine history (present in 20-30% of patients) supports CVS diagnosis and may guide treatment selection 2, 3
• Screen for and treat postural orthostatic tachycardia syndrome, which can improve overall functional status 2

Common Pitfalls to Avoid

Missing the prodromal window is the most critical error—abortive therapy effectiveness drops dramatically if not administered immediately at symptom onset 1, 3, 4

Overlooking retching and nausea as equally disabling symptoms leads to inadequate treatment; don't focus solely on vomiting 2, 4

Misinterpreting self-soothing behaviors (excessive water drinking, self-induced vomiting for temporary relief) as malingering—these are specific to CVS 2

Ignoring psychiatric comorbidities worsens episode frequency and delays effective management 3, 4