Can antihistamines help relieve pruritus associated with cough in a patient with acute tonsillopharyngogle (tonsillopharyngitis)?

Antihistamines for Pruritus and Cough in Acute Tonsillopharyngitis

First-generation antihistamines (such as diphenhydramine or chlorpheniramine) can provide symptomatic relief for pruritus and may help with associated cough in acute tonsillopharyngitis, but they should not be used as primary therapy and work best when upper airway secretions contribute to symptoms. 1

Understanding the Clinical Context

Acute tonsillopharyngitis is predominantly viral in origin, and when cough accompanies throat symptoms, it typically indicates upper airway involvement rather than lower respiratory tract infection. 1 The key is recognizing that:

• Most pharyngitis cases are viral (rhinovirus, coronavirus, adenovirus, influenza), and patients with cough, nasal congestion, or hoarseness are more likely to have viral illness. 1
• Pruritus in this context usually reflects histamine-mediated inflammation in the throat and upper airways, which can trigger both itching and cough reflexes. 2

Role of First-Generation Antihistamines

For Pruritus Relief

• Diphenhydramine is highly effective for histamine-mediated pruritus associated with acute allergic reactions and upper respiratory inflammation. 2
• In a randomized controlled trial, 100% of patients with pruritus receiving diphenhydramine had clinically significant relief compared to 60% receiving H2-blockers alone. 2
• First-generation antihistamines work through both H1-receptor blockade and anticholinergic effects, providing relief within 30-60 minutes of oral administration. 1

For Cough Associated with Upper Airway Symptoms

• First-generation antihistamines can reduce cough when it originates from upper airway secretions triggering the cough reflex, not through direct antitussive action. 1, 3, 4
• The mechanism involves anticholinergic activity restricted to nasal airways, reducing secretions that drip posteriorly and stimulate throat irritation. 1, 3
• Antihistamine-decongestant combinations were significantly more effective than placebo (p<0.01) for cough associated with upper respiratory tract infections in adults. 5
• However, antihistamines alone (without decongestants) showed no benefit over placebo for cough in multiple trials. 5, 6

Practical Treatment Algorithm

Step 1: Assess the Clinical Picture

• If tonsillopharyngitis presents with pruritus (itchy throat) and cough with postnasal drip or nasal congestion, first-generation antihistamines are appropriate. 1, 4
• If symptoms include fever, rigors, tonsillar exudates, or severe dysphagia without upper airway symptoms, focus on treating the pharyngitis itself rather than symptomatic cough suppression. 1

Step 2: Choose Appropriate Antihistamine Therapy

For pruritus alone:

• Diphenhydramine 25-50 mg every 4-6 hours as needed. 7, 2
• Chlorpheniramine 4 mg every 4-6 hours as an alternative. 4, 8

For pruritus with cough and upper airway secretions:

• Combination therapy is superior: First-generation antihistamine plus decongestant (e.g., chlorpheniramine 4 mg + pseudoephedrine 60 mg every 6 hours, or sustained-release formulations twice daily). 4, 5
• Monotherapy with antihistamines alone is not recommended for cough, as evidence shows no benefit over placebo. 5, 6

Step 3: Dosing Strategy to Minimize Sedation

• Start with bedtime dosing for several days before advancing to multiple daily doses, allowing tolerance to sedative effects to develop. 4, 9
• Improvement typically occurs within days to 2 weeks of starting treatment. 4, 9

Critical Caveats and Contraindications

• Second-generation antihistamines (cetirizine, loratadine, fexofenadine) are ineffective for cough because they lack anticholinergic and CNS-penetrant properties. 1, 4, 9
• Avoid first-generation antihistamines in patients with:
  • Symptomatic benign prostatic hypertrophy or urinary retention. 4, 9
  • Narrow-angle glaucoma. 1, 4
  • Significant cognitive impairment or elderly patients at high fall risk. 4, 9
• Monitor for anticholinergic side effects: dry mouth, constipation, urinary retention, and sedation that can impair performance even without subjective drowsiness. 4, 9
• Antihistamines should never replace epinephrine if anaphylaxis is suspected, and they work too slowly (30-120 minutes to peak effect) for acute severe allergic reactions. 1

When Antihistamines Are NOT Appropriate

• For isolated pharyngeal pain without pruritus or upper airway symptoms, analgesics (acetaminophen, NSAIDs) are more appropriate. 1
• For dry cough without secretions or postnasal drip, central cough suppressants (dextromethorphan or codeine) are preferred over antihistamines. 1, 8
• Antibiotics are not indicated for viral tonsillopharyngitis with cough unless group A Streptococcus is confirmed or pneumonia is suspected. 1

Bottom Line for Clinical Practice

Use first-generation antihistamines for symptomatic relief of pruritus in acute tonsillopharyngitis, and add a decongestant if cough with upper airway secretions is present. 4, 5 This approach addresses the histamine-mediated itching directly while the anticholinergic properties reduce secretions that trigger cough. 1, 3 However, recognize that these are adjunctive symptomatic measures—they do not shorten illness duration or treat the underlying viral infection. 1