What is the cause of recurrent nausea, vomiting, and headache in a 35-year-old patient with a similar episode 1 month ago?

Recurrent Nausea, Vomiting, and Headache: Key Diagnostic Considerations

You are most likely missing cyclic vomiting syndrome (CVS), migraine without aura, or cannabinoid hyperemesis syndrome—all of which present with recurrent stereotypical episodes of nausea, vomiting, and headache in young adults. 1

Primary Differential Diagnosis

Cyclic Vomiting Syndrome (CVS)

CVS should be your leading consideration given the recurrent pattern with a similar episode 1 month ago. 1

Key diagnostic features to assess:

• 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, separated by at least 1 week of baseline health 1
• Absence of vomiting between episodes (though milder symptoms like nausea may persist) 1
• Prodromal symptoms occur in approximately 65% of patients, lasting a median of 1 hour before vomiting onset—patients may report an impending sense of doom, panic, or inability to communicate effectively 1
• Constitutional symptoms during episodes: fatigue, feeling hot/cold, mental fog, restlessness, anxiety, headache, bowel urgency, diaphoresis, flushing, or shakiness 1
• Abdominal pain is present in most CVS patients and should NOT exclude the diagnosis 1
• Early morning onset is typical, though episodes can occur anytime 1

Critical question to ask: Does the patient use cannabis regularly for >1 year? This may indicate cannabinoid hyperemesis syndrome rather than CVS 2

Migraine Without Aura

Migraine is a strong alternative diagnosis, especially given the headache prominence. 1

Specific features to elicit:

• Recurrent moderate to severe headache that is unilateral and/or pulsating 1
• Accompanying symptoms: photophobia, phonophobia, nausea, and/or vomiting 1
• Duration: 4-72 hours when untreated 1
• Family history of migraine strongly supports the diagnosis 1
• Age of onset at or around puberty increases suspicion 1

Medication-Overuse Headache

If the patient has been taking analgesics frequently, consider this diagnosis. 1

• Headache on ≥15 days/month in someone with pre-existing headache disorder 1
• Regular overuse for >3 months: non-opioid analgesics on ≥15 days/month OR any other acute medication on ≥10 days/month 1

Critical "Red Flag" Assessments

You must actively exclude life-threatening causes before settling on a benign diagnosis:

Subarachnoid Hemorrhage (SAH)

• "Worst headache of life" described by 80% of SAH patients 1
• Sentinel/warning headache in 20% of patients, occurring 2-8 weeks before major rupture 1
• Associated features: brief loss of consciousness (53%), nuchal rigidity (35%), focal neurological deficits 1
• Misdiagnosis rate: 12% in recent data, associated with 4-fold higher mortality 1
• Action required: Non-contrast head CT is mandatory if SAH suspected 1

Intracranial Space-Occupying Lesion

• Headache brought on by sneezing, coughing, or exercise 1
• Headache with postures/maneuvers that raise intracranial pressure 1
• Associated weight loss, memory changes, or personality changes 1
• Focal neurological symptoms on examination 1

Meningitis

• Unexplained fever 1
• Neck stiffness 1

Essential Initial Workup

The American Gastroenterological Association recommends the following basic laboratory evaluation for vomiting: 2

• Complete blood count (assess infection, inflammation, blood loss) 2
• Serum electrolytes and glucose (metabolic derangements, dehydration) 2
• Liver function tests (hepatic causes) 2
• Serum lipase (pancreatitis) 2
• Urinalysis (hydration status, urinary causes) 2
• Pregnancy test in any woman of childbearing age 3, 4

Additional testing based on clinical suspicion:

• Thyroid-stimulating hormone if endocrine cause suspected 5
• Urine drug screen to assess for cannabis use (cannabinoid hyperemesis syndrome) 2
• Non-contrast head CT if any concern for intracranial pathology 1
• Upper endoscopy or upper GI imaging for persistent vomiting to exclude obstructive lesions 2
• Gastric emptying scintigraphy (4-hour study) if gastroparesis suspected 1

Management Approach

Acute Episode Treatment

For active vomiting episodes, the American Gastroenterological Association recommends: 2

• Ondansetron 8 mg sublingual/oral every 4-6 hours (first-line) 2
• Promethazine 12.5-25 mg oral/rectal every 4-6 hours (first-line alternative) 2
• Prochlorperazine 5-10 mg every 6-8 hours or 25 mg suppository every 12 hours 2
• IV crystalloids for dehydration and electrolyte replacement 2

CVS-Specific Abortive Therapy

If CVS is confirmed, early intervention during the prodromal phase is critical: 1

• Sumatriptan plus antiemetics during prodromal phase 2
• Patient education on recognizing prodromal symptoms and "rehearsing" early intervention 1

Migraine-Specific Treatment

For migraine attacks, use acute medication early in the headache phase: 1

• NSAIDs (aspirin, ibuprofen, or diclofenac potassium) as first-line 1
• Triptans as second-line 1
• Prokinetic antiemetics (domperidone or metoclopramide) for nausea/vomiting 1
• Avoid opioids and barbiturates 1

Common Pitfalls to Avoid

1. Failing to obtain non-contrast head CT when SAH is possible—this is the most common diagnostic error leading to preventable mortality 1

2. Dismissing abdominal pain as excluding CVS—most CVS patients have abdominal pain during episodes 1

3. Not asking about cannabis use—prolonged use (>1 year) suggests cannabinoid hyperemesis syndrome rather than CVS 2

4. Performing gastric emptying studies <4 hours—shorter durations are inaccurate for detecting gastroparesis 1

5. Missing medication-overuse headache—frequent analgesic use can perpetuate the cycle 1

6. Not checking pregnancy status—pregnancy is the most common endocrinologic cause of nausea in women of childbearing age 3