Most Likely Diagnosis: Postinfectious Upper Airway Cough Syndrome (UACS) with Acute Laryngitis
The most likely diagnosis is postinfectious upper airway cough syndrome (UACS) with acute laryngitis, representing the expected natural progression of a viral upper respiratory infection rather than bacterial superinfection. 1
Clinical Reasoning
Why This Is NOT Bacterial Sinusitis
Your patient does not meet criteria for acute bacterial rhinosinusitis (ABRS) despite 18 days of symptoms. The American College of Physicians and IDSA define bacterial sinusitis by three specific patterns: 2
- Persistent symptoms without improvement for >10 days
- Severe symptoms: fever >39°C with purulent discharge for ≥3 consecutive days
- Worsening symptoms after initial improvement ("double sickening")
Your patient's course shows progressive improvement of symptoms (throat resolved day 14, sinus congestion improving and thinning by day 18), which is inconsistent with bacterial infection. 2, 1 The American Academy of Otolaryngology-Head and Neck Surgery explicitly states that colored nasal discharge results from neutrophil influx during normal viral infection progression and is not specific for bacterial infection. 3
Why This IS Postinfectious UACS with Laryngitis
The American College of Chest Physicians identifies postinfectious UACS by: 1
- History of preceding URI (✓ - started 17 days ago)
- Persistent cough with postnasal drip (✓ - semi-productive cough, mucus pooling)
- Symptoms extending into weeks 2-3 post-URI (✓ - day 18)
- Progressive improvement rather than worsening (✓ - throat resolved, sinus thinning)
The hoarseness with vocal cord involvement represents acute laryngitis, a common component of viral URIs that can persist 2-3 weeks. 4
Recommended Treatment
Discontinue Current Ineffective Therapies
Stop Sinex (oxymetazoline) immediately - prolonged use beyond 3-5 days causes rebound congestion and may be perpetuating her unilateral nasal obstruction. 1
Continue Flonase (fluticasone) - intranasal corticosteroids provide symptomatic relief and are appropriate for persistent nasal symptoms. 2, 1
Continue guaifenesin - it reduces cough reflex sensitivity in patients with URI. 5
Add First-Generation Antihistamine-Decongestant Combination
The American College of Chest Physicians recommends first-generation antihistamine combined with oral decongestant (pseudoephedrine, not phenylephrine) as primary treatment for postinfectious UACS. 1 This combination decreases cough severity and hastens resolution of postnasal drip. 6
Prednisone Considerations
The 10mg prednisone dose started on day 13 is subtherapeutic for significant anti-inflammatory effect but may provide modest benefit. Consider either increasing to therapeutic dosing (40-60mg daily for 5-7 days) for laryngitis or discontinuing entirely, as evidence for low-dose steroids in this context is limited. 1
Voice Rest and Laryngitis Management
- Absolute voice rest for 48-72 hours
- Humidification (cool mist)
- Adequate hydration
- Avoid throat clearing (swallow instead)
When Antibiotics ARE Indicated
Do NOT prescribe antibiotics unless: 2, 1
- Symptoms worsen after current improvement
- New high fever develops (>39°C)
- Severe unilateral facial pain/swelling emerges
- Symptoms fail to resolve by 8 weeks total duration
The American College of Physicians found that antibiotics in acute rhinosinusitis have a number needed to treat of 18 but number needed to harm of 8. 2
Other Possible Diagnoses to Monitor
Pertussis (Whooping Cough)
Given her history of post-URI complications and the persistent cough, consider pertussis if: 6
- Cough becomes paroxysmal with inspiratory whoop
- Post-tussive vomiting develops
- Cough persists beyond 3 weeks without improvement
Complications Requiring Urgent Evaluation
Given her history of periorbital cellulitis and other complications, immediately reassess if: 1
- Vision changes occur
- Severe unilateral facial pain/swelling develops
- High fever returns
- Mental status changes
- Severe headache with neck stiffness
Contagion Status
She is likely no longer significantly contagious. 1
- Viral shedding peaks days 1-3 and substantially decreases by days 7-10
- At day 18 with improving symptoms, viral load should be minimal to absent
- Basic respiratory hygiene (handwashing, covering coughs) remains prudent
Critical Pitfalls to Avoid
Do not prescribe antibiotics based on symptom duration alone - the trajectory (improving vs. worsening) determines bacterial likelihood, not the calendar. 2, 1
Do not assume persistent cough requires antibiotics - postinfectious cough lasting 3-8 weeks is expected and self-limited. 1
Do not continue oxymetazoline beyond 5 days - this causes rebound congestion and may be worsening her unilateral obstruction. 1
Watch for true bacterial complications given her history - but treat based on clinical worsening, not persistence of viral symptoms. 2