In a healthy adult (18‑65) with an 8‑week non‑productive cough that worsens when lying down or after meals and is accompanied by throat clearing, nasal congestion, and intermittent rhinorrhea, what is the most likely diagnosis and recommended first‑line treatment?

Upper Airway Cough Syndrome (UACS)

The most likely diagnosis is Upper Airway Cough Syndrome (UACS), and the recommended first-line treatment is a first-generation antihistamine/decongestant combination (such as dexbrompheniramine plus sustained-release pseudoephedrine or azatadine plus sustained-release pseudoephedrine) taken for 1-2 weeks, with improvement expected within days to 2 weeks. 1

Clinical Presentation and Diagnosis

This patient's presentation is classic for UACS:

• Chronic non-productive cough (>8 weeks) that worsens when lying down 2
• Throat clearing – a cardinal symptom of UACS 1
• Nasal congestion and intermittent rhinorrhea – indicating upper airway involvement 1
• Postprandial worsening – suggests possible coexisting gastroesophageal reflux, though UACS remains the primary diagnosis given the prominent upper airway symptoms 1

UACS accounts for 18.6%-81.8% of chronic cough cases and is the single most common cause of chronic cough in adults. 2, 3 The diagnosis is primarily clinical and confirmed by response to specific therapy, not by symptoms or physical findings alone. 1

Critical Diagnostic Consideration: "Silent" UACS

Approximately 20% of patients have "silent" postnasal drip with no obvious symptoms yet still respond to treatment. 1 This means the absence of typical findings (visible postnasal drainage, cobblestoning) does not rule out UACS. 1

First-Line Treatment Algorithm

Step 1: Initiate Antihistamine/Decongestant Combination (Days 1-14)

Start immediately with a first-generation antihistamine/decongestant combination – this has the strongest evidence as the most effective first-line treatment for UACS. 1 Specific effective combinations include:

• Dexbrompheniramine maleate plus sustained-release pseudoephedrine sulfate 1
• Azatadine maleate plus sustained-release pseudoephedrine sulfate 1
• Chlorpheniramine with sustained-release pseudoephedrine 1

Why first-generation antihistamines? Older-generation antihistamines are superior to newer non-sedating antihistamines due to their anticholinergic properties, which provide additional drying effects. 1 Newer-generation antihistamines are ineffective for non-allergic causes of UACS. 1

Dosing strategy to minimize sedation: Start with once-daily dosing at bedtime for a few days before increasing to twice-daily therapy. 1

Expected timeline: Most patients see improvement within days to 2 weeks of initiating therapy. 1

Step 2: Add Intranasal Corticosteroids if No Response After 1-2 Weeks

If symptoms persist despite adequate antihistamine/decongestant treatment for 1-2 weeks, add intranasal corticosteroids such as fluticasone 100-200 mcg daily for a 1-month trial. 1 Intranasal corticosteroids are effective for both allergic and non-allergic rhinitis-related UACS. 1

Step 3: Consider Alternative Agents for Contraindications

For patients with contraindications to decongestants (hypertension, cardiovascular disease, glaucoma):

• Ipratropium bromide nasal spray (42 mcg per spray, 2 sprays per nostril 4 times daily) provides anticholinergic drying effects without systemic cardiovascular side effects and is specifically effective for reducing rhinorrhea. 1

Adjunctive Therapy: Nasal Saline Irrigation

High-volume saline nasal irrigation (150 mL) improves symptoms through mechanical removal of mucus, enhanced ciliary activity, and disruption of inflammatory mediators. 1 Nasal irrigation is more effective than saline spray because irrigation better expels secretions. 1

Important Monitoring and Side Effects

Common Side Effects

• Dry mouth and transient dizziness 1
• Sedation (mitigated by bedtime dosing initially) 1

Serious Side Effects Requiring Monitoring

• Insomnia, urinary retention, jitteriness, tachycardia 1
• Worsening hypertension – monitor blood pressure after initiating decongestant therapy 1
• Increased intraocular pressure in glaucoma patients 1

When to Evaluate for Other Causes

If symptoms persist despite adequate upper airway treatment for 2 weeks, proceed with sequential evaluation for other common causes of chronic cough: 1

1. Asthma/Non-asthmatic eosinophilic bronchitis (NAEB) – accounts for 14.6%-41.3% of chronic cough 3

   • Consider bronchial provocation testing if spirometry is normal 3
   • Initiate inhaled corticosteroids; response may take up to 8 weeks 1

2. Gastroesophageal reflux disease (GERD) – accounts for 4.6%-85.4% of chronic cough 3

   • Can occur without gastrointestinal symptoms ("silent GERD") 1
   • Initiate omeprazole 20-40 mg twice daily before meals for at least 8 weeks plus dietary modifications 1
   • Improvement may take 2 weeks to several months 1

Critical principle: Up to 67% of patients have multiple simultaneous causes of chronic cough. 3 Therefore, maintain all partially effective treatments rather than discontinuing them prematurely, as UACS, asthma, and GERD together account for approximately 90% of chronic cough cases. 1, 3

Common Pitfalls to Avoid

1. Failing to recognize "silent" UACS – approximately 20% of patients have no obvious postnasal drip symptoms yet respond to treatment. 1

2. Using newer-generation antihistamines – these are less effective for non-allergic causes of UACS. 1

3. Discontinuing partially effective treatments prematurely – chronic cough is frequently multifactorial, requiring additive treatment strategies. 3

4. Using topical nasal decongestants (oxymetazoline, xylometazoline) for more than 3-5 consecutive days – this causes rhinitis medicamentosa (rebound congestion). 1

5. Confusing GERD with UACS – both can cause pharyngeal inflammation and throat symptoms; they may coexist. 1

Follow-Up and Reassessment

Schedule a follow-up visit within 4-6 weeks after the initial evaluation to assess cough severity using validated scales and verify treatment adherence. 2, 3 If cough persists beyond 8 weeks despite systematic treatment of UACS, asthma, and GERD, consider referral to a specialized cough clinic. 2