What is the recommended treatment for paroxysmal cough, especially in a patient with hypothyroidism?

Treatment of Paroxysmal Cough

For paroxysmal cough, immediately initiate empirical treatment with a macrolide antibiotic (azithromycin preferred) without waiting for laboratory confirmation, as this presentation strongly suggests pertussis (whooping cough) until proven otherwise. 1, 2

Immediate Clinical Action

• Start azithromycin immediately as the first-line antibiotic due to superior tolerability and compliance compared to other macrolides 2
• Alternative options include erythromycin 1-2 g/day for 2 weeks or clarithromycin if azithromycin is contraindicated 2
• Isolate the patient for 5 days from the start of antibiotic treatment to prevent transmission, as pertussis is highly contagious 1, 2
• Do not delay treatment waiting for culture results—early therapy within the first 2 weeks decreases paroxysmal episodes and prevents spread 1, 2

Diagnostic Confirmation

• Order a nasopharyngeal aspirate or Dacron swab for Bordetella pertussis culture, which is the only definitive diagnostic method 1, 2
• Bacterial isolation confirms the diagnosis with certainty 1, 2
• PCR is not routinely recommended due to lack of universally validated techniques 1, 2
• Consider paired acute and convalescent serology (IgG/IgA against pertussis toxin) for presumptive diagnosis if a 4-fold increase is demonstrated 1, 2

Symptomatic Management for Paroxysmal Cough

• Inhaled ipratropium bromide is the first-line symptomatic treatment to attenuate cough paroxysms 1, 2
• For severe paroxysms after ruling out other causes, prescribe prednisone 30-40 mg daily for a short, finite period (2-3 weeks with taper) 1, 2
• Dextromethorphan 60 mg (not over-the-counter doses) can be used when other measures fail for optimal cough reflex suppression 2
• Avoid codeine—it has no greater efficacy than dextromethorphan but worse side effects 2

Treatments That Do NOT Work

• Do not use long-acting β-agonists, antihistamines, corticosteroids (inhaled), or pertussis immunoglobulin for pertussis-related cough, as there is no evidence of benefit 1
• After 2 weeks of symptoms, antibiotic benefit is limited but may still be offered to prevent transmission 1, 2

Special Consideration for Hypothyroidism

• While thyroiditis is a rare cause of chronic persistent cough, this is relevant only after extensive evaluation excludes common causes and only if cough resolves with thyroid suppressive therapy 3
• Hypothyroidism itself may reduce airway beta-adrenergic responsiveness, but this does not change the acute management of paroxysmal cough 4
• The paroxysmal nature of the cough makes pertussis the primary concern, not thyroid-related cough 1, 2

Critical Pitfalls to Avoid

• Do not wait for laboratory confirmation to start antibiotics—delay reduces effectiveness and allows continued transmission 2
• Do not forget isolation protocols—the patient remains contagious until 5 days after starting antibiotics 1, 2
• Do not use subtherapeutic doses of dextromethorphan—over-the-counter doses are insufficient; 60 mg is required 2
• If the patient does not have pertussis and this is post-infectious cough, do not use antibiotics as they have no role in viral post-infectious cough 1, 5