What is the treatment for cyclic vomiting syndrome?

Treatment of Cyclic Vomiting Syndrome

For adults with moderate-to-severe CVS (≥4 episodes/year lasting >2 days), start amitriptyline 25 mg at bedtime as first-line prophylaxis, titrating to 75-150 mg nightly (goal 1-1.5 mg/kg), combined with sumatriptan 20 mg intranasal plus ondansetron 8 mg sublingual as abortive therapy at the first sign of prodromal symptoms. 1, 2

Disease Severity Classification

Before initiating treatment, classify CVS severity to determine therapeutic intensity 1:

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

Prophylactic Therapy (Inter-episodic Phase)

First-Line Agent

Amitriptyline is the first-line prophylactic medication with 67-75% response rates 1, 2:

• Start 25 mg at bedtime, titrate to 75-150 mg nightly 1
• Goal dose: 1-1.5 mg/kg at bedtime 1
• Critical monitoring: Obtain baseline ECG due to QTc prolongation risk 1

Second-Line Prophylactic Options

If amitriptyline fails or is not tolerated, use these alternatives 1, 2:

• 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 Prophylactic Therapy

Aprepitant (neurokinin-1 antagonist) can be added to other prophylactic agents 1, 2:

• Adolescents 40-60 kg: 80 mg 2-3 times weekly 1
• Adolescents >60 kg and adults: 125 mg 2-3 times weekly 1

Lifestyle Modifications

All patients require non-pharmacologic interventions 1:

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

Abortive Therapy (Prodromal Phase)

The probability of successfully aborting a CVS episode is highest when medications are taken immediately at the onset of prodromal symptoms - missing this window dramatically reduces effectiveness 1.

Standard Abortive Regimen

Combination therapy is essential - nearly all patients require multiple agents rather than monotherapy 1:

• Sumatriptan 20 mg intranasal (first-line) 1, 2

  • Administer in head-forward position to optimize nasal receptor contact 1
  • Can repeat once after 2 hours, maximum 2 doses per 24 hours 1
  • Subcutaneous injection is an alternative if intranasal not tolerated 1

• Ondansetron 8 mg sublingual (first-line antiemetic) 1

  • Can repeat every 4-6 hours during episode 1

Additional Abortive Agents

Build an "abortive cocktail" with these additional medications 1:

• 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 1:
  • Alprazolam (sublingual or rectal) 1
  • Lorazepam 1
  • Diphenhydramine 1
  • Caution: Use sedatives carefully in adolescents with substance abuse risk 1

Emergency Department Management (Emetic Phase)

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

Fluid and Electrolyte Management

• IV dextrose-containing fluids for rehydration and metabolic support 1
• Aggressive electrolyte replacement 1

Pharmacologic Management

• Ondansetron 8 mg IV every 4-6 hours 1
• Ketorolac IV as first-line non-narcotic analgesia for severe abdominal pain 1
• Benzodiazepines IV for sedation in a quiet, dark room 1
• Droperidol or haloperidol for refractory cases 1

Recovery Phase

Focus on gradual reintroduction of nutrition 1:

• Rehydration with electrolyte-rich fluids (sports drinks) 1
• Small, frequent sips of nutrient drinks as tolerated 1

Critical Clinical Considerations

Cannabis Screening

Screen all patients for cannabis use before diagnosing CVS 1, 3:

• Cannabis use >4 times weekly for >1 year suggests cannabinoid hyperemesis syndrome (CHS) rather than CVS 1
• Hot water bathing occurs in 48% of CVS patients without cannabis use and is NOT pathognomonic for CHS 3

Psychiatric Comorbidities

Screen for anxiety, depression, and panic disorder - present in 50-60% of CVS patients 3:

• Treating underlying anxiety can decrease CVS episode frequency 3
• Many patients experience prodromal anxiety with "impending sense of doom" 3
• Consider cognitive-behavioral therapy for psychological triggers 3

Migraine Connection

A personal or family history of migraine (present in 20-30% of patients) supports CVS diagnosis and may guide treatment selection 3

Common Pitfalls to Avoid

• Missing the prodromal window: Abortive therapy effectiveness drops dramatically if not given immediately at symptom onset 1, 3
• Inadequate sedation: Insufficient sedation can worsen symptoms and prolong episodes 3
• Overlooking retching and nausea: These symptoms are equally disabling as vomiting and require treatment 1
• Misdiagnosing psychiatric symptoms: Anxiety and depression are comorbidities, not the cause of CVS 3
• Delayed diagnosis: CVS affects approximately 2% of the US population but remains underrecognized, leading to years of diagnostic delays and unnecessary procedures 4, 3