What is the best approach to managing cyclic vomiting syndrome in a patient, particularly in children and young adults, with symptoms including severe vomiting, abdominal pain, and nausea?

Management of Cyclic Vomiting Syndrome

The best approach to managing CVS requires phase-specific treatment: amitriptyline 25-150 mg nightly as first-line prophylaxis for moderate-severe disease (≥4 episodes/year lasting >2 days), combined with immediate abortive therapy using sumatriptan 20 mg intranasal plus ondansetron 8 mg sublingual at the first sign of prodromal symptoms. 1, 2

Disease Classification and Treatment Intensity

CVS severity determines your treatment strategy. Classify patients as mild (<4 episodes/year, each <2 days, no ED visits) or moderate-severe (≥4 episodes/year, >2 days, requiring ED visits or hospitalizations). 1, 2

• Mild CVS requires only abortive therapy 2
• Moderate-severe CVS requires both prophylactic and abortive therapy 2
• Approximately one-third of adults with CVS become disabled, making aggressive treatment essential 3

Critical Diagnostic Considerations Before Treatment

Screen all patients for cannabis use before confirming CVS diagnosis—use >4 times weekly for >1 year suggests cannabinoid hyperemesis syndrome (CHS) rather than CVS and requires 6 months of cessation to differentiate. 2, 4

• Hot water bathing occurs in 48% of CVS patients who don't use cannabis, so this behavior alone does not distinguish CHS from CVS 3
• Screen for anxiety, depression, and panic disorder—present in 50-60% of CVS patients—as treating underlying psychiatric comorbidities can decrease episode frequency 2, 3
• Personal or family history of migraine supports CVS diagnosis and may guide treatment selection 2, 3

Phase-Specific Treatment Approach

Prophylactic Therapy (Inter-Episodic Phase)

Start amitriptyline 25 mg at bedtime and titrate to 75-150 mg nightly (goal dose 1-1.5 mg/kg)—this has a 67-75% response rate and is first-line prophylaxis. 2, 3

• Obtain baseline ECG due to QTc prolongation risk 2
• Second-line 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 2
  • Levetiracetam: Start 500 mg twice daily, titrate to 1000-2000 mg daily in divided doses; monitor CBC 2
  • Zonisamide: Start 100 mg daily, titrate to 200-400 mg daily; monitor electrolytes and renal function twice yearly 2
• Aprepitant (neurokinin-1 antagonist) as adjunctive therapy: 80 mg 2-3 times weekly for adolescents 40-60 kg, or 125 mg 2-3 times weekly for adolescents >60 kg 2

Abortive Therapy (Prodromal Phase)

The probability of successfully aborting an episode is highest when medications are taken immediately at the onset of prodromal symptoms—educate patients to recognize their stereotypical prodrome (impending doom, panic, anxiety, diaphoresis, mental fog, restlessness). 1, 2, 3

Approximately 65% of patients experience prodromal symptoms lasting a median of 1 hour before vomiting begins 1

Standard abortive regimen:

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

Additional abortive agents to consider:

• Promethazine 12.5-25 mg oral/rectal every 4-6 hours 2
• Prochlorperazine 5-10 mg every 6-8 hours or 25 mg suppository every 12 hours 2
• Sedatives (alprazolam, lorazepam, diphenhydramine) to truncate the episode—use caution in adolescents with substance abuse risk 2

Emergency Department Management (Emetic Phase)

If home abortive therapy fails and the patient presents with uncontrollable vomiting:

• Aggressive IV fluid replacement with dextrose-containing fluids for rehydration and metabolic support 2, 3
• Ondansetron 8 mg IV every 4-6 hours 2
• IV ketorolac as first-line non-narcotic analgesia for severe abdominal pain 2
• IV benzodiazepines for sedation in a quiet, dark room 2, 3
• Droperidol or haloperidol for refractory cases 2, 3
• Check and correct electrolyte abnormalities immediately 3

Patients in the emetic phase often appear agitated and have difficulty communicating—providers may need to rely on caregivers or an individualized treatment plan 1, 3

Recovery Phase

Focus on rehydration with electrolyte-rich fluids (sports drinks) and gradual introduction of nutrient drinks as tolerated. 3

Essential Lifestyle Modifications for All Patients

Implement these non-pharmacologic interventions regardless of disease severity:

• Maintain regular sleep schedule and avoid sleep deprivation 2, 3
• Avoid prolonged fasting 2, 3
• Identify and avoid individual triggers (stress in 70-80% of patients, including positive events like birthdays and vacations; hormonal fluctuations; travel; motion sickness; acute infections; surgery) 1, 2
• Stress management techniques 2, 3

Common Pitfalls to Avoid

Missing the prodromal window dramatically reduces abortive therapy effectiveness—"rehearse" with patients the actions they should take at the first sign of prodromal symptoms. 1, 2, 4

• Do not misinterpret self-soothing behaviors (excessive water drinking, self-induced vomiting) as malingering—these provide temporary relief and are specific to CVS 1, 3
• Do not overlook retching and nausea—these symptoms are equally disabling as vomiting and require aggressive treatment 1, 4
• Do not ignore abdominal pain—it is present in most patients during CVS episodes and should not preclude diagnosis 1
• Do not underestimate disease severity—approximately one-third of adults become disabled 3

Recognition of Clinical Features

CVS episodes are stereotypical for each patient, with recognizable patterns 1:

• Most episodes occur in early morning hours 1
• Episodes last <7 days with at least 1 week of baseline health between episodes 1, 3
• Prodromal symptoms include impending sense of doom, panic, fatigue, mental fog, restlessness, anxiety, headache, bowel urgency, diaphoresis, flushing 1, 2
• Constitutional, cognitive, autonomic, and motor symptoms accompany the prodromal and emetic phases 1