In an otherwise healthy adult with acute viral bronchitis presenting with throat irritation and post‑nasal‑drip cough, what first‑generation antihistamine brand names (with generic names) and recommended adult dosing are appropriate for symptomatic relief?

First-Generation Antihistamines for Acute Viral Bronchitis with Post-Nasal Drip Cough

For an adult with acute viral bronchitis presenting with throat irritation and post-nasal drip cough, prescribe a first-generation antihistamine/decongestant combination such as brompheniramine 12 mg with sustained-release pseudoephedrine 120 mg, twice daily. 1

Recommended First-Generation Antihistamine Combinations

The ACCP guidelines strongly recommend first-generation antihistamine/decongestant combinations as the evidence-based standard treatment for acute cough from the common cold and upper airway cough syndrome 1. The following combinations have demonstrated efficacy in randomized controlled trials:

Primary Options with Brand Names

• Brompheniramine 12 mg + pseudoephedrine 120 mg (sustained-release), twice daily 1, 2

  • Brand names: Bromfed, Lodrane

• Dexbrompheniramine 6 mg + pseudoephedrine 120 mg (sustained-release), twice daily 2, 3

  • Brand names: Drixoral (discontinued in US but formulation remains standard)

• Azatadine 1 mg + pseudoephedrine 120 mg (sustained-release), twice daily 3, 4

  • Brand name: Trinalin (discontinued but formulation remains in guidelines)

Alternative Single-Agent First-Generation Antihistamines

If decongestants are contraindicated (glaucoma, benign prostatic hypertrophy, uncontrolled hypertension), consider these first-generation antihistamines alone, though they are less effective than combinations 3, 4:

• Diphenhydramine (Benadryl): 25-50 mg four times daily 3, 5
• Chlorpheniramine (Chlor-Trimeton): 4 mg four times daily 3
• Brompheniramine: 4 mg four times daily 3

Why First-Generation Antihistamines Work

First-generation antihistamines are effective for acute viral bronchitis cough primarily through their anticholinergic properties, not their antihistamine effects 1. They reduce nasal secretions and limit inflammatory mediators that trigger the cough reflex 1, 3. This explains why newer, non-sedating antihistamines (cetirizine, loratadine, fexofenadine) are ineffective for this indication—they lack anticholinergic activity and do not penetrate the central nervous system 1, 6.

Dosing Strategy to Minimize Sedation

• Start with once-daily dosing at bedtime for the first few days, then increase to twice-daily dosing to minimize sedation 3, 4
• Most patients experience improvement within days to 2 weeks of starting treatment 1, 3

Critical Contraindications and Monitoring

Absolute Contraindications to Decongestants 1

• Symptomatic benign prostatic hypertrophy or urinary retention
• Narrow-angle glaucoma
• Severe uncontrolled hypertension
• Congestive heart failure
• Concurrent MAO inhibitor use

Monitoring Requirements

• Monitor blood pressure after initiating decongestant therapy, as pseudoephedrine can cause hypertension, tachycardia, palpitations, and insomnia 2, 4
• Monitor for anticholinergic side effects: dry mouth, constipation, urinary retention, increased intraocular pressure 3

Special Populations

• Elderly patients: Avoid first-generation antihistamines in those with cognitive impairment, glaucoma, or urinary retention 2
• Performance impairment: Warn patients about potential sedation affecting driving and work performance, even without subjective awareness 3

What NOT to Use

• Second-generation antihistamines (cetirizine, loratadine, fexofenadine) with or without decongestants are ineffective for acute cough and should not be prescribed 1, 6
• Antibiotics are not indicated for acute viral bronchitis and do not improve outcomes 1, 7
• Dextromethorphan may provide modest symptomatic relief but is less effective than first-generation antihistamine/decongestant combinations 1, 5

When to Escalate Treatment

If cough persists beyond 2 weeks despite adequate antihistamine/decongestant therapy 3, 4:

• Consider adding intranasal corticosteroids (fluticasone 100-200 mcg daily) for a 1-month trial 4
• Evaluate for alternative diagnoses: asthma, gastroesophageal reflux disease, chronic sinusitis 1, 3
• Obtain sinus imaging if purulent nasal discharge persists beyond 10 days 4

Common Pitfalls to Avoid

• Do not prescribe antibiotics during the first week of symptoms, even with purulent nasal discharge—this is typical of viral infections and does not indicate bacterial infection 1, 4
• Do not use topical nasal decongestants (oxymetazoline) for more than 3-5 days due to risk of rhinitis medicamentosa 2, 4
• Do not overlook contraindications to decongestants in patients with cardiovascular disease or urinary symptoms 1, 2
• Do not assume lack of response means wrong diagnosis—approximately 20% of patients have "silent" post-nasal drip with no obvious symptoms yet still respond to treatment 3, 4