What is the diagnosis and management for a 19-year-old patient presenting with vomiting for 2 hours, diffuse headache, and sweating?

Acute Presentation: Vomiting, Headache, and Sweating in a 19-Year-Old

This presentation requires immediate assessment for life-threatening conditions including meningitis, subarachnoid hemorrhage, anaphylaxis, and acute coronary syndrome, with urgent evaluation of vital signs, level of consciousness, and meningeal signs to determine if the patient requires emergency intervention. 1

Immediate Assessment Priorities

Critical Red Flags to Evaluate Immediately

• Check vital signs and hemodynamic stability: Tachycardia with hypotension suggests anaphylaxis or cardiovascular collapse; bradycardia with hypertension suggests increased intracranial pressure 1
• Assess level of consciousness: Any alteration suggests meningitis, encephalitis, or intracranial pathology requiring immediate intervention 1, 2
• Examine for meningeal signs: Neck stiffness, photophobia, and Kernig's/Brudzinski's signs indicate possible meningitis 1, 2
• Evaluate for urticaria or angioedema: These are the most common manifestations of anaphylaxis, though they may be absent in rapidly progressive cases 1
• Assess respiratory status: Stridor, wheezing, or dyspnea suggests anaphylaxis requiring immediate epinephrine 1

Distinguish Vasovagal Reaction from Life-Threatening Causes

The vasodepressor (vasovagal) reaction is commonly confused with serious pathology but has distinct features: bradycardia (not tachycardia), cool and pale skin, normal or increased blood pressure, and absence of urticaria or bronchospasm 1. Tachycardia is the rule in anaphylaxis and acute coronary syndrome, making this a critical distinguishing feature 1.

Differential Diagnosis by Pattern

If Fever is Present

• Aseptic or bacterial meningitis: Severe bilateral headache with fever, vomiting, and meningeal signs requires immediate lumbar puncture after ruling out increased intracranial pressure 1, 2
• All patients with aseptic meningitis have headache, typically severe and bilateral in 95% of cases, with abrupt onset or "worst headache ever" in 59% 2
• Prodromal symptoms (malaise, myalgia, gastrointestinal symptoms) occur in 46% of meningitis cases 2

If Chest Pain or Cardiac Symptoms Present

• Acute coronary syndrome: Diffuse chest discomfort with sweating (diaphoresis), nausea, and vomiting in a young adult, especially female, requires immediate ECG and cardiac biomarkers 1
• Sweating is more frequent in men with acute myocardial infarction, while nausea and vomiting are more frequent in women 1

If Exposure History or Urticaria Present

• Anaphylaxis: Rapid onset after exposure to allergen with vomiting, sweating, and headache requires immediate epinephrine 0.3-0.5 mg IM, even before urticaria appears 1
• Increased vascular permeability can transfer 50% of intravascular fluid into extravascular space within 10 minutes, causing hemodynamic collapse with minimal cutaneous manifestations 1

If Episodic Pattern with Well Periods

• Cyclic vomiting syndrome (CVS): Stereotypical episodes of acute-onset vomiting lasting <7 days with prodromal symptoms including diaphoresis, anxiety, headache, and impending sense of doom 3, 4
• Diaphoresis occurs in 70-80% of CVS patients during episodes 3
• Screen for cannabis use >4 times weekly for >1 year, which suggests cannabinoid hyperemesis syndrome rather than CVS 3

Immediate Management Algorithm

Step 1: Rule Out Anaphylaxis (First 5 Minutes)

• If urticaria, angioedema, respiratory compromise, or hypotension present: Give epinephrine 0.3-0.5 mg IM immediately 1
• Assess airway, breathing, circulation before any other intervention 1

Step 2: Rule Out Meningitis/CNS Infection (First 15 Minutes)

• If fever + headache + vomiting + meningeal signs: Obtain blood cultures, start empiric antibiotics immediately, then perform lumbar puncture 1, 2
• CT brain before LP only if focal neurologic signs, papilledema, or decreased consciousness 1, 2
• Lumbar puncture findings: increased protein, increased WBC with lymphocytic predominance suggests aseptic meningitis; positive gram stain requires immediate antibiotic escalation 1, 2

Step 3: Rule Out Acute Coronary Syndrome (First 15 Minutes)

• If chest discomfort + sweating + nausea/vomiting: Obtain 12-lead ECG immediately and cardiac biomarkers 1
• ST-segment elevation or depression requires immediate cardiology consultation and dual antiplatelet therapy 1

Step 4: If Above Ruled Out, Treat Symptomatically

• Ondansetron 4-8 mg orally/sublingual or IV as first-line antiemetic 3, 5, 6
• IV fluid resuscitation with normal saline or lactated Ringer's for patients unable to tolerate oral intake 3, 4
• For suspected CVS during prodrome: Sumatriptan 20 mg intranasal + ondansetron 8 mg sublingual immediately 3

Critical Pitfalls to Avoid

• Do not dismiss severe headache with vomiting as "gastroenteritis" without ruling out meningitis and subarachnoid hemorrhage 2
• Do not wait for urticaria to appear before treating suspected anaphylaxis—respiratory or cardiovascular symptoms alone warrant epinephrine 1
• Do not attribute all symptoms to anxiety without excluding organic causes—altered mental status, fever, or focal neurologic signs require immediate workup 1, 2
• Missing the prodromal window in CVS dramatically reduces abortive therapy effectiveness—medications must be given at first symptom onset 3

When to Obtain Imaging

• CT brain indicated for: Focal neurologic deficits, papilledema, altered consciousness, or "worst headache of life" to rule out hemorrhage or mass lesion before LP 1, 7, 2
• Upper GI series indicated for: Bilious vomiting suggesting bowel obstruction—this is a surgical emergency 5