What are the common causes of post‑nasal drip and the recommended first‑line management?

Causes and Management of Post-Nasal Drip

First-Line Treatment Recommendation

Start immediately with a first-generation antihistamine/decongestant combination (such as dexbrompheniramine plus sustained-release pseudoephedrine or azatadine plus sustained-release pseudoephedrine) as the most effective evidence-based treatment for post-nasal drip, now termed Upper Airway Cough Syndrome (UACS). 1

---

Common Causes of Post-Nasal Drip

The differential diagnosis includes multiple etiologies that must be systematically considered:

Allergic Causes

• Allergic rhinitis accounts for approximately 28% of UACS cases and presents with seasonal or perennial symptoms, sneezing, and extranasal involvement such as itching of eyes and ears 2, 1
• Seasonal allergic rhinitis is triggered by outdoor antigens (grass and tree pollens), while perennial forms involve indoor antigens (dust mite, cockroach) 2

Non-Allergic Causes

• Chronic rhinitis represents approximately 22% of cases 1
• Vasomotor rhinitis presents with sudden onset of profuse, thin, watery secretions triggered by odors, temperature changes, humidity shifts, eating (gustatory rhinitis), or alcohol ingestion 2
• Nonallergic rhinitis with eosinophilia (NARES) presents similarly to vasomotor rhinitis but includes nasal and ocular pruritus with eosinophils in nasal secretions despite negative allergy testing 2

Infectious and Structural Causes

• Chronic sinusitis or nasal polyps account for approximately 31% of cases 3
• Postinfectious rhinitis follows upper respiratory tract infections and typically responds to first-generation antihistamine/decongestant combinations 2
• Bacterial sinusitis may cause productive or nonproductive cough and can be "clinically silent" without typical acute sinusitis findings 2, 1
• Anatomic abnormalities including deviated septum, adenoid vegetation (16% of cases), and polyps around the sphenoid ostium 2, 3, 4

Other Causes

• Rhinitis medicamentosa from overuse of topical nasal decongestants beyond 3-5 days 1, 5
• Gastroesophageal reflux disease (GERD) frequently mimics UACS with upper respiratory symptoms 2, 1
• Chronic nasopharyngitis (3% of cases) 3

---

Recommended Management Algorithm

Step 1: Initial Empiric Therapy (Days 1-14)

Prescribe a first-generation antihistamine/decongestant combination as the cornerstone of treatment 1:

• Specific effective combinations include dexbrompheniramine maleate plus sustained-release pseudoephedrine sulfate, or azatadine maleate plus sustained-release pseudoephedrine sulfate 1
• To minimize sedation, start with once-daily dosing at bedtime for a few days before increasing to twice-daily therapy 1
• Most patients will see improvement within days to 2 weeks of initiating therapy 1
• Common side effects include dry mouth and transient dizziness 1
• Monitor for insomnia, urinary retention, jitteriness, tachycardia, worsening hypertension, and increased intraocular pressure in glaucoma patients 1

Important caveat: Newer-generation non-sedating antihistamines (cetirizine, fexofenadine, loratadine) are ineffective for non-allergic UACS and should not be used 1

Step 2: Add Intranasal Corticosteroids (If No Response After 1-2 Weeks)

Add intranasal corticosteroids such as fluticasone 100-200 mcg daily for a 1-month trial alongside the antihistamine/decongestant combination 1:

• Intranasal corticosteroids are the most effective monotherapy for both allergic and non-allergic rhinitis 1, 6, 5
• A full month trial is necessary to assess response 1, 6
• For confirmed allergic rhinitis, add intranasal corticosteroids immediately rather than waiting 1

Step 3: Alternative or Adjunctive Therapies

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

• Use ipratropium bromide nasal spray 42 mcg per spray, 2 sprays per nostril 4 times daily, which provides anticholinergic drying effects without systemic cardiovascular side effects 1, 6, 5

Adjunctive therapy for all patients:

• High-volume saline nasal irrigation (150 mL per nostril) twice daily mechanically removes secretions and improves mucociliary function, and is more effective than saline spray 1, 6, 5
• Longer treatment duration (mean 7.5 months) shows better results than shorter courses 1

For allergic rhinitis specifically:

• Oral leukotriene inhibitors decrease symptoms of allergic rhinitis 1
• Nasal corticosteroids, antihistamines, and/or cromolyn are first-line options 1

Step 4: Sequential Evaluation for Other Causes (If No Response After 2 Weeks)

If symptoms persist despite adequate upper airway treatment for 2 weeks, proceed with sequential evaluation 1:

1. Evaluate for asthma/non-asthmatic eosinophilic bronchitis:

   • Consider bronchial provocation testing if spirometry is normal 1
   • Trial of inhaled corticosteroids may be warranted 1

2. Evaluate for GERD:

   • Initiate empiric therapy with proton pump inhibitor (omeprazole 20-40 mg twice daily before meals) for at least 8 weeks plus dietary modifications 1
   • Improvement in cough from GERD treatment may take up to 3 months 1
   • GERD frequently mimics UACS and may coexist with it 2, 1

3. Obtain sinus imaging (CT scan):

   • If persistent nasal symptoms despite topical therapy 1
   • Air-fluid levels indicate acute bacterial sinusitis requiring antibiotics 1
   • Mucosal thickening <8mm is associated with sterile nasal puncture in 100% of cases 1

Step 5: Antibiotic Therapy (When Indicated)

Reserve antibiotics for clear evidence of bacterial sinusitis 1:

• Purulent nasal discharge persisting >10 days without improvement 6
• "Double sickening" (initial improvement followed by worsening) 6
• Facial pain, fever, or air-fluid levels on imaging 1
• Minimum of 3 weeks of antibiotics effective against H. influenzae, mouth anaerobes, and S. pneumoniae for chronic sinusitis 1

Important: Yellowish-green nasal discharge does NOT indicate bacterial infection requiring antibiotics, as purulent discharge is typical of viral infections 6

---

Critical Pitfalls to Avoid

Diagnostic Pitfalls

• Do not overlook "silent" UACS: Approximately 20% of patients have no obvious postnasal drip symptoms (no visible drainage, no throat clearing, normal pharyngeal examination) yet still respond to UACS-directed treatment 2, 1, 6
• Do not rely solely on physical examination: The absence of visible posterior pharyngeal drainage or cobblestoning does not rule out UACS; response to specific therapy is the pivotal diagnostic factor 1
• Do not confuse GERD with UACS: Both can cause pharyngeal inflammation and throat symptoms; GERD may mimic or coexist with postnasal drip 2, 1

Treatment Pitfalls

• Never use topical nasal decongestants (oxymetazoline, xylometazoline) for more than 3-5 consecutive days due to the risk of rhinitis medicamentosa (rebound congestion) 1, 5
• Do not use newer-generation antihistamines for non-allergic UACS: They are ineffective for non-allergic causes and should not be used for acute cough management 1
• Do not discontinue partially effective treatments prematurely: UACS, asthma, and GERD together account for approximately 90% of chronic cough cases and often coexist; maintain all partially effective treatments 1
• Monitor blood pressure after initiating decongestant therapy: Decongestants can cause hypertension, tachycardia, insomnia, and worsening of glaucoma 1, 5

Timing Considerations

• Complete resolution may take several weeks to a few months despite starting appropriate therapy 1
• Reassess after 2-3 weeks of treatment with the antihistamine/decongestant combination 1
• If cough persists beyond 8 weeks despite systematic treatment of UACS, asthma, and GERD, consider referral to a specialized cough clinic 1

---

Special Populations and Considerations

Pediatric Patients

• In children aged ≤14 years, common adult causes (asthma, GERD, chronic bronchitis) should NOT be presumed to be common causes 6
• Start with intranasal fluticasone 100-200 mcg once daily for at least one month as the most effective monotherapy 6
• High-volume saline irrigation with 150 mL per nostril twice daily is recommended 6

Patients with Cardiovascular Contraindications

• Avoid first-generation antihistamine/decongestant combinations in patients with severe hypertension, cardiac arrhythmias, or on cardiac medications 5
• Use ipratropium bromide nasal spray as an alternative 1, 5
• Intranasal corticosteroids remain safe and effective 5