What is the likely diagnosis and treatment for a patient with symptoms of a runny nose and coughing, possibly indicating a viral upper respiratory infection?

Viral Upper Respiratory Infection: Diagnosis and Management

Most Likely Diagnosis

The patient almost certainly has a viral upper respiratory infection (URI), which is the single most common cause of acute cough and runny nose. 1, 2 Over 200 different viruses can cause this syndrome, including rhinoviruses, coronaviruses, parainfluenza viruses, respiratory syncytial virus, adenoviruses, and enteroviruses. 1

Clinical Course and Natural History

The typical viral URI follows a predictable pattern that is critical for management decisions:

• Days 1-3: Fever and constitutional symptoms predominate, with peak viral shedding and highest contagiousness. 3
• Days 3-6: Respiratory symptoms (nasal congestion, cough) reach maximum severity as constitutional symptoms fade. 3
• Days 7-10: Most uncomplicated viral URIs resolve, though nasal congestion and cough commonly persist into weeks 2-3. 1, 3
• Beyond 10 days: If symptoms persist without any improvement, bacterial superinfection becomes significantly more likely (approximately 60% probability). 4

Key Diagnostic Pitfall to Avoid

Do not assume yellow or green nasal discharge indicates bacterial infection. 4 Mucopurulent secretions commonly occur after a few days of viral infection due to neutrophil influx and represent normal viral illness progression, not bacterial superinfection. 1, 2, 4 The nasal discharge naturally transitions from clear to purulent to clear again during uncomplicated viral resolution. 4

When Antibiotics Are NOT Indicated

Antibiotics have no role and should be avoided when: 2, 4

• Symptoms have been present for less than 10 days without worsening 4
• Yellow/green nasal discharge is present (this alone is not diagnostic of bacterial infection) 4
• Cough and congestion are present without other concerning features 4

When to Consider Bacterial Superinfection (Acute Bacterial Rhinosinusitis)

Antibiotics should only be considered if one of three specific patterns emerges: 2, 4

1. Persistent symptoms: Nasal discharge or daytime cough lasting ≥10 days without any improvement 2, 4
2. Worsening/biphasic course: Initial improvement followed by worsening or new onset of fever, cough, or nasal discharge after 5-7 days 2, 4
3. Severe onset: High fever (>39°C) and purulent nasal discharge for at least 3 consecutive days with the patient appearing ill 2, 4

Recommended Treatment for Viral URI

For uncomplicated viral URI, treatment is purely symptomatic: 2, 4

• Analgesics (acetaminophen or ibuprofen) for pain/fever 5
• Nasal saline irrigation 2
• Adequate hydration 4
• Antihistamines and/or decongestants for congestion (though evidence is limited) 5

Management of Postinfectious Cough (3-8 Weeks Duration)

If cough persists beyond the acute phase but less than 8 weeks, this represents postinfectious upper airway cough syndrome (UACS): 2

• First-line treatment: First-generation antihistamine (e.g., dexbrompheniramine 6 mg twice daily or azatadine 1 mg twice daily) combined with sustained-release pseudoephedrine (120 mg twice daily) 1, 2
• Alternative: Inhaled ipratropium bromide if first-generation antihistamines are contraindicated or ineffective 1, 2
• Avoid: Newer non-sedating antihistamines (e.g., loratadine, terfenadine) are ineffective for postinfectious cough 1

The mechanism of benefit from first-generation antihistamines is likely their anticholinergic properties rather than antihistamine effects. 1

Contagiousness Timeline

• Peak contagiousness: Days 1-3 of symptomatic illness 3
• Typical contagious period: 3-7 days, though viral shedding can continue for ≥7 days after symptom onset 3
• Important caveat: Viral shedding can begin before symptoms appear, complicating prevention efforts 3

Red Flags Requiring Urgent Evaluation

Reassess immediately if any of the following develop: 2

• High fever returning after initial improvement
• Severe unilateral facial pain or swelling
• Vision changes
• Mental status changes or severe headache with neck stiffness
• Symptoms persisting beyond 8 weeks total duration

Critical Clinical Takeaway

The decision to prescribe antibiotics should be based on time and symptom pattern, not on the color of nasal discharge. 4 The vast majority of patients with runny nose and cough have self-limited viral infections that will resolve with symptomatic treatment alone within 7-10 days. 1, 6 Inappropriate antibiotic use causes avoidable adverse events, increases antibiotic resistance, and provides no benefit for viral infections. 4