What is the differential diagnosis and treatment for a patient presenting with a persistent dry cough, mild sore throat, and dryness, triggered by cold environments and talking, without fever, shortness of breath, or myalgias?

Differential Diagnosis and Treatment for Persistent Dry Cough with Mild Sore Throat

This presentation is most consistent with acute viral upper respiratory tract infection (common cold) or early postinfectious cough, and should be treated with symptomatic management including first-generation antihistamine/decongestant combination and inhaled ipratropium if cough is severe—antibiotics have no role and should not be prescribed. 1, 2

Differential Diagnosis

Most Likely: Acute Viral Upper Respiratory Tract Infection

• The 4-day duration of dry cough with mild sore throat and dryness, triggered by cold air and talking, without fever or systemic symptoms, is classic for viral upper respiratory tract infection (common cold) 1, 2
• The absence of fever, shortness of breath, tachycardia (>100 bpm), tachypnea (>24 breaths/min), or focal chest findings makes pneumonia extremely unlikely and eliminates the need for chest radiography 1, 2
• Cough triggered by cold environment and talking suggests upper airway irritation and postnasal drip (upper airway cough syndrome) 1

Important to Rule Out: Pertussis

• Pertussis must be considered if paroxysmal coughing, post-tussive vomiting, or inspiratory whooping sound develops, even in vaccinated patients 1, 3
• If pertussis is suspected, obtain nasopharyngeal culture and start macrolide antibiotics (azithromycin or clarithromycin) immediately to reduce coughing severity and prevent transmission 1, 3

Consider if Symptoms Persist Beyond 3 Weeks: Postinfectious Cough

• Cough persisting 3-8 weeks after initial respiratory infection is classified as postinfectious cough and requires different management 1
• Mechanisms include persistent postnasal drip, bronchial hyperresponsiveness, and mucus hypersecretion 1

Consider if Symptoms Persist Beyond 2-3 Weeks: Cough-Variant Asthma

• Cough-variant asthma should be suspected if persistent dry cough worsens at night or with cold exposure, but typically requires >2-3 weeks duration for diagnosis 1
• Diagnosis requires either improvement with bronchodilator therapy or positive methacholine challenge test 1
• Physical examination and spirometry are often normal in cough-variant asthma 1

Treatment Approach

Immediate Management (Days 1-7)

Do NOT prescribe antibiotics 1, 2

• Antibiotics have no role in viral acute bronchitis or upper respiratory tract infection 1, 2
• They provide no benefit, contribute to antimicrobial resistance, and cause adverse effects including allergic reactions and C. difficile infection 1, 2

Symptomatic relief with first-generation antihistamine/decongestant combination 1, 3

• Start with once-daily dosing at bedtime (e.g., brompheniramine/pseudoephedrine or chlorpheniramine/phenylephrine) for 2-3 days, then advance to twice-daily to minimize sedation 3
• This combination has been shown in double-blind placebo-controlled studies to decrease cough severity and hasten resolution of cough and postnasal drip 1
• Critical pitfall: Do NOT use nasal decongestant sprays for more than 3-5 days due to rebound congestion risk 3, 2, 4

Inhaled ipratropium bromide for severe cough 1, 3, 2

• Prescribe 2-3 puffs four times daily if cough significantly compromises quality of life 3, 2
• This has the strongest evidence for attenuating postinfectious cough with fewer systemic side effects 3

Supportive measures 2, 4

• Voice rest to reduce vocal fold irritation 4
• Adequate hydration to maintain mucosal moisture 4
• Simple home remedies like honey and lemon are cost-effective with no adverse effects 2
• Analgesics (acetaminophen or NSAIDs) for sore throat discomfort 4

Optional: Cough suppressants 1, 5

• Central acting antitussives such as dextromethorphan or codeine may be considered when other measures fail 1, 5

If Symptoms Persist at 2 Weeks

Add intranasal corticosteroid spray 3

• Fluticasone or mometasone to decrease airway inflammation 3

Consider inhaled corticosteroids if cough adversely affects quality of life 1, 3

• May require up to 8 weeks of treatment for complete resolution 1
• Pitfall: Some inhaled corticosteroids (particularly beclomethasone) may themselves induce cough due to aerosol constituents—consider switching to triamcinolone if this occurs 1

If Symptoms Persist Beyond 3 Weeks

Re-evaluate for alternative diagnoses 1, 2

• Cough persisting >3 weeks requires systematic evaluation for upper airway cough syndrome, asthma, and gastroesophageal reflux disease (GERD) 1
• Consider methacholine challenge testing to evaluate for cough-variant asthma if clinical suspicion exists 1
• Consider empiric GERD treatment even without typical GI symptoms, as GERD can present with cough alone 1, 3

For severe postinfectious cough paroxysms 1, 2

• Consider prednisone 30-40 mg daily for a short finite period (typically 1 week) only after ruling out other common causes 1, 2

Critical Pitfalls to Avoid

• Never prescribe antibiotics for viral upper respiratory tract infection or acute bronchitis 1, 2
• Do not use nasal decongestant sprays beyond 3-5 days 3, 2, 4
• Do not ignore the possibility of pertussis if paroxysmal cough or post-tussive vomiting develops 1, 3
• Do not assume bacterial infection based on colored mucus—this does not differentiate viral from bacterial infection 4
• Do not diagnose "unexplained cough" until completing systematic evaluation of upper airway cough syndrome, asthma, and GERD with adequate treatment trials 3