What is the appropriate evaluation and management for a 39‑year‑old man with sudden onset nausea, vomiting, chills, and heat sensations that occur mainly in the morning after coughing?

Evaluation and Management of Post-Tussive Nausea and Vomiting

This 39-year-old man presenting with post-tussive vomiting (nausea and vomiting triggered by coughing) most likely has pertussis (whooping cough) and requires immediate nasopharyngeal culture for Bordetella pertussis followed by macrolide antibiotic therapy if confirmed or highly suspected.

Primary Diagnostic Consideration: Pertussis

The combination of cough with post-tussive vomiting is pathognomonic for pertussis until proven otherwise 1, 2. The ACCP guidelines explicitly state that when a patient has cough lasting ≥2 weeks accompanied by paroxysms of coughing and post-tussive vomiting, the diagnosis of B. pertussis infection should be made unless another diagnosis is proven 1, 2.

Key Clinical Features Supporting Pertussis:

• Post-tussive vomiting (vomiting after coughing episodes)
• Morning predominance (when coughing is often worse)
• Paroxysmal nature of symptoms
• Chills and heat waves (consistent with systemic response)
• Adult presentation (often atypical without classic "whoop")

Immediate Diagnostic Workup

Order a nasopharyngeal aspirate or Dacron swab for culture - this is the gold standard and only certain way to confirm B. pertussis 1, 2. Culture isolation provides definitive diagnosis 1.

Alternative/Adjunctive Testing:

• Paired acute and convalescent sera for presumptive diagnosis: A fourfold increase in IgG or IgA antibodies to pertussis toxin (PT) or filamentous hemagglutinin (FHA) confirms recent infection 1, 2
• PCR testing is NOT recommended as routine clinical practice due to lack of universally validated techniques 1, 2

Treatment Algorithm

If Pertussis Confirmed or Highly Suspected:

Initiate macrolide antibiotic immediately 2:

• Erythromycin, clarithromycin, or azithromycin
• Isolate patient for 5 days from treatment start
• Early treatment (within first few weeks) diminishes coughing paroxysms and prevents disease spread 2
• Treatment beyond the early catarrhal phase is less effective but may still be offered 2

Treatments to AVOID in Pertussis:

The guidelines are explicit: Do NOT use long-acting β-agonists, antihistamines, corticosteroids, or pertussis immunoglobulin - there is no evidence of benefit 1, 2.

If Pertussis is Ruled Out: Post-Infectious Cough Management

If symptoms have been present 3-8 weeks following a respiratory infection and pertussis is excluded, consider post-infectious cough 1, 2:

Stepwise Treatment Approach:

1. First-line: Inhaled ipratropium - may attenuate cough (Grade B evidence) 1, 2
2. Second-line: Inhaled corticosteroids - if cough persists and affects quality of life 1, 2
3. For severe paroxysms: Prednisone 30-40 mg daily for short course after ruling out upper airway cough syndrome, asthma, and GERD 1, 2
4. Last resort: Central antitussives (codeine or dextromethorphan) when other measures fail 1, 2

Antibiotics have NO role in post-infectious cough unless bacterial sinusitis is present 1, 2.

Management of Associated Nausea/Vomiting

While treating the underlying cough etiology, symptomatic management of nausea may include 3, 4:

• Fluid and electrolyte replacement if dehydration present
• Small, frequent meals
• Antiemetics: Serotonin antagonists (ondansetron) or dopamine antagonists (metoclopramide) for acute symptom control
• Use antiemetics for shortest duration necessary

Critical Pitfalls to Avoid

1. Missing pertussis diagnosis: Adults often lack the classic "whoop" - post-tussive vomiting is the key clue
2. Delaying macrolide therapy: Early treatment is crucial for efficacy and preventing transmission
3. Using ineffective therapies: Corticosteroids and bronchodilators do NOT help pertussis 1, 2
4. Relying on PCR alone: Culture remains the gold standard 1, 2
5. Assuming viral post-infectious cough without excluding pertussis: The timeline and post-tussive vomiting mandate pertussis evaluation first

Timeline Considerations

• <3 weeks of symptoms: Likely acute viral illness
• 3-8 weeks: Post-infectious cough or pertussis window
• >8 weeks: Consider alternative diagnoses beyond post-infectious cough 1, 2

The sudden onset with morning predominance and post-tussive vomiting in this 39-year-old strongly suggests pertussis requiring immediate diagnostic confirmation and macrolide therapy.