What are the possible causes of sudden onset vomiting occurring three to four times per week?

Sudden Onset Vomiting 3-4 Times Weekly: Differential Diagnosis

The most likely diagnosis for sudden onset vomiting occurring 3-4 times per week in an adult is Cyclic Vomiting Syndrome (CVS), which requires evaluation against Rome IV diagnostic criteria and exclusion of other serious causes including gastrointestinal obstruction, metabolic disorders, and medication effects. 1

Primary Consideration: Cyclic Vomiting Syndrome

CVS should be strongly suspected when vomiting episodes meet specific diagnostic criteria:

• Stereotypical episodes of acute-onset vomiting lasting less than 7 days 1
• At least 3 discrete episodes per year, with 2 occurring in the prior 6 months 1
• Episodes separated by at least 1 week of baseline health 1
• Absence of vomiting between episodes, though milder symptoms like nausea, occasional vomiting, and dyspepsia may persist 1

Key clinical features that support CVS diagnosis:

• Episodes often begin during night or early morning with rapid onset 2
• Uncontrollable bouts of retching and vomiting lasting hours to days 1
• Associated symptoms include pallor, lethargy, anorexia, nausea, and abdominal pain 2
• Hot water bathing or showering provides temporary relief in approximately 48% of CVS patients who don't use cannabis 1
• Personal or family history of migraine headaches is a supportive criterion 1

Critical Triggers to Identify

Stress is the most common CVS trigger, confirmed in 70-80% of patients 1:

• Negative stressors: death, work conflicts, family conflicts 1
• Positive stressors: birthdays, family reunions, vacations 1
• Sleep deprivation 1
• Hormonal fluctuations during menstrual cycle 1
• Travel and motion sickness 1
• Physiological stressors: acute infections, surgery 1
• Less common: prolonged fasting, intense exercise 1

Essential Comorbidities to Assess

CVS frequently coexists with specific conditions that guide diagnosis and management:

• Mood disorders (anxiety, depression, panic disorder) present in 50-60% of patients 1
• Migraine headaches present in 20-30% of patients 1
• Autonomic imbalances including postural orthostatic tachycardia syndrome 1
• Seizure disorders in approximately 3% of patients 1

Alternative Diagnoses to Exclude

Before confirming CVS, rule out these serious causes:

Gastrointestinal Causes

• Gastroenteritis and food poisoning are the most common causes of acute vomiting 3
• Intestinal obstruction (bilious vomiting is a red flag requiring immediate surgical evaluation) 4
• Gastroparesis 5

Medication-Related Causes

• Medication side effects should always be suspected in any vomiting presentation 3
• Review all current medications and recent additions 6

Metabolic and Endocrine Causes

• Addison's disease 1
• Hypothyroidism 1
• Hepatic porphyria 1
• Diabetic ketoacidosis 7

Neurologic Causes

• Increased intracranial pressure 7
• Intracranial mass lesions 7
• Patients with any localizing neurologic symptoms require brain imaging and neurology referral 1

Pregnancy

• Pregnancy should always be suspected in women of childbearing age 3

Diagnostic Workup

Initial basic workup for episodic vomiting includes:

• Complete blood count 1
• Serum electrolytes and glucose 1
• Liver function testing 1
• Lipase 1
• Urinalysis 1
• One-time esophagogastroduodenoscopy or upper gastrointestinal imaging to exclude obstructive lesions 1

Important pitfall: If esophagogastroduodenoscopy is performed soon after a CVS episode, recognize epiphenomena of recent vomiting (mild gastritis, erythematous streaking, Mallory-Weiss tear, esophagitis) as not being causal 1

Avoid these unnecessary tests:

• Repeated esophagogastroduodenoscopy or upper GI imaging 1
• Routine gastric emptying scans (few CVS patients have delayed emptying; results during episodes are uninterpretable) 1

Cannabis Use Considerations

Many CVS patients use cannabis, raising concerns for Cannabinoid Hyperemesis Syndrome (CHS):

• CHS is considered a subset of CVS when prolonged (>1 year) and heavy cannabis use (>4 times weekly, often daily) precedes symptom onset 1
• In CVS, cannabis use is more occasional and often postdates the onset of episodic vomiting 1
• 6 months of cannabis cessation or at least 3 typical cycle lengths is required to retrospectively diagnose CHS 1
• If vomiting continues after this cessation period, CHS can be ruled out 1
• Critical point: Patients with ongoing cannabis use should still be offered abortive and prophylactic therapy, as these can be effective even with continued use 1

Severity Classification

CVS severity determines management intensity:

• Mild CVS: <4 episodes/year, each lasting <2 days, without ED visits or hospitalizations 1
• Moderate-severe CVS: ≥4 episodes/year, each lasting >2 days, requiring at least 1 ED visit or hospitalization 1

Red Flags Requiring Urgent Evaluation

Seek immediate evaluation if any of these develop:

• Bilious (green) vomiting indicates intestinal obstruction and requires immediate surgical evaluation 4
• Hematemesis or hematochezia suggests GI bleeding or intussusception 4
• Altered mental status or lethargy 4
• Signs of severe dehydration 4
• Abdominal pain that worsens or localizes to right lower quadrant 4
• Fever that increases 4

Management Approach

For confirmed CVS, management focuses on three phases:

Prodromal Phase Management

• This is the ideal time for abortive therapies 1
• Earlier intervention has higher probability of successfully aborting an episode 1
• Patient education on recognizing prodromal symptoms is imperative 1

Trigger Management

• Help patients recognize and develop strategies to eliminate or mitigate triggers 1
• Treat comorbid conditions: improving anxiety may decrease CVS episode frequency 1

Prophylactic Therapy

• Consider for moderate-severe CVS 1
• Treatment of postural orthostatic tachycardia syndrome may improve overall functional status 1