In a 34‑year‑old woman with prior low‑grade fever, nasal congestion, ethmoid sinus pain treated with phenylephrine, chlorpheniramine maleate, and paracetamol, now having persistent nighttime dry cough with clear sputum, hypotension, and swollen non‑erythematous turbinates, what is the most likely diagnosis and appropriate next steps?

Most Likely Diagnosis: Post-Infectious Upper Airway Cough Syndrome (UACS)

This 34-year-old woman has post-infectious upper airway cough syndrome (UACS) following a viral upper respiratory infection, characterized by the classic timeline of initial URI symptoms (fever, nasal congestion, sinus pain) that resolved, followed by persistent cough with clear phlegm and swollen non-erythematous turbinates. 1

Clinical Reasoning

The presentation fits the diagnostic pattern of post-infectious UACS:

• Timeline: Initial URI symptoms 2 weeks ago with complete resolution after symptomatic treatment, followed by persistent cough for 1 week 1, 2
• Cough characteristics: Dry cough triggered by throat itching, worse at night, now with clear phlegm production—classic for post-viral airway inflammation and post-nasal drainage 1
• Physical findings: Swollen non-erythematous turbinates indicate ongoing upper airway inflammation without bacterial infection 1
• Duration: Cough lasting 1 week post-URI is within the expected 3-8 week window for post-infectious cough 2

The hypotension (95/61) is likely constitutional for this thin patient and not acutely concerning given normal other vital signs and no symptoms of hemodynamic compromise. 2

Next Steps: Evidence-Based Treatment Algorithm

First-Line Treatment (Start Immediately)

Prescribe a first-generation antihistamine-decongestant combination PLUS intranasal corticosteroid:

• Chlorpheniramine 4 mg + Phenylephrine 10 mg (or equivalent combination) every 4-6 hours 1, 3
  • Note: Phenylephrine oral efficacy is questionable per recent data 4, but guideline recommendations prioritize first-generation antihistamine-decongestant combinations 1, 3
  • Alternative: Brompheniramine + Pseudoephedrine if available 3

PLUS

• Fluticasone propionate nasal spray 100-200 mcg (1-2 sprays per nostril) once daily for 1 month 1, 3

Expected response time: Days to 1-2 weeks 1, 3

Supportive Measures

• High-volume saline nasal irrigation (150 mL per nostril twice daily) to mechanically remove secretions and improve mucociliary clearance 3
• Guaifenesin 200-400 mg every 4 hours (up to 6 times daily) as needed for mucus clearance 2
• Elevate head of bed and avoid supine position immediately after meals 2

Second-Line Treatment (If No Improvement After 1-2 Weeks)

Add inhaled ipratropium bromide 2-3 puffs (17-34 mcg per puff) four times daily 2

• This has the strongest evidence for attenuating post-infectious cough 2
• Expected response: 1-2 weeks 2

Third-Line Evaluation (If Cough Persists Beyond 2-3 Weeks)

Systematically evaluate for the three most common causes of chronic cough:

1. Asthma/Cough-Variant Asthma 1, 2

   • Obtain spirometry with bronchodilator response
   • Consider methacholine challenge if spirometry normal
   • Empiric trial: Inhaled corticosteroid (fluticasone 220 mcg or budesonide 360 mcg twice daily) + bronchodilator
   • Response time: Up to 8 weeks 2

2. GERD (even without GI symptoms—"silent GERD") 1, 2

   • Empiric trial: Omeprazole 40 mg twice daily before meals for at least 8 weeks
   • Add dietary modifications (avoid late meals, caffeine, alcohol, fatty foods)
   • Response time: 2 weeks to several months 2

3. Bacterial Sinusitis 1

   • Obtain sinus CT if purulent discharge, facial pain/pressure, or symptoms >10 days
   • Antibiotics only if air-fluid levels or clear bacterial infection documented 1, 2

Critical Red Flags Requiring Immediate Re-Evaluation

Order chest X-ray if any of the following develop: 2

• Cough persists beyond 8 weeks
• Hemoptysis (any amount)
• Fever recurrence
• Unintentional weight loss
• Night sweats
• Dyspnea or chest pain

Consider pertussis if: 2

• Paroxysmal coughing develops
• Post-tussive vomiting occurs
• Inspiratory "whoop" sound emerges

Common Pitfalls to Avoid

• Do NOT prescribe antibiotics—this is post-viral inflammation, not bacterial infection 1, 2
• Do NOT use newer-generation antihistamines (cetirizine, loratadine, fexofenadine)—they are ineffective for non-allergic UACS 1, 3
• Do NOT use topical nasal decongestants (oxymetazoline) for >3-5 days due to rebound congestion risk 3
• Do NOT overlook "silent" UACS—approximately 20% of patients have no obvious post-nasal drip symptoms yet respond to treatment 1, 3
• Do NOT stop partially effective treatments prematurely—chronic cough is often multifactorial; maintain all therapies that provide partial benefit while adding next intervention 2

Follow-Up Plan

• Reassess in 1-2 weeks to evaluate treatment response 1, 3
• If cough persists at 3 weeks, add ipratropium and consider post-infectious cough diagnosis 2
• If cough persists beyond 8 weeks, reclassify as chronic cough and systematically evaluate for UACS/asthma/GERD 1, 2
• Monitor blood pressure after starting decongestant therapy, especially given baseline hypotension 3