Antibiotics Are Not Recommended for a 6-Week Cough
For a cough lasting 6 weeks (subacute cough), antibiotics have no role in treatment unless there is confirmed pertussis or bacterial sinusitis—the cause is not bacterial infection and antibiotic therapy provides no benefit. 1
Understanding the 6-Week Cough Timeline
A 6-week cough falls into the subacute category (3-8 weeks), most commonly representing postinfectious cough following a viral upper respiratory infection. 1, 2 The key distinction is:
- Acute cough: <3 weeks
- Subacute cough: 3-8 weeks (your patient is here)
- Chronic cough: >8 weeks 2
Why Antibiotics Don't Work
The ACCP guidelines explicitly state that therapy with antibiotics has no role in postinfectious cough, as the cause is not bacterial infection. 1 More than 90% of patients presenting with acute cough have a viral syndrome, and postinfectious inflammation—not ongoing bacterial infection—drives the persistent cough. 1
The British Thoracic Society found that long-term macrolide antibiotics (like azithromycin) are ineffective in improving any outcomes in chronic cough, with randomized trials showing no significant difference in cough frequency. 3
Two Critical Exceptions Where Antibiotics ARE Indicated
1. Pertussis (Whooping Cough)
If the patient has paroxysmal coughing, post-tussive vomiting, or inspiratory whooping sounds, suspect pertussis and prescribe a macrolide antibiotic (azithromycin, clarithromycin, or erythromycin). 1 Early treatment within the first few weeks diminishes coughing paroxysms and prevents disease spread. 1 However, treatment beyond this early period is unlikely to help the patient. 1
2. Bacterial Sinusitis
If there are clinical features of bacterial sinusitis (purulent nasal discharge, facial pain/pressure, fever), antibiotics may be appropriate. 1
What Actually Works for Subacute Postinfectious Cough
First-Line Treatment
- Inhaled ipratropium bromide: The only recommended inhaled anticholinergic agent for cough suppression, shown to attenuate postinfectious cough. 1, 2
Second-Line Options (if ipratropium fails)
- Inhaled corticosteroids: Consider when cough adversely affects quality of life and persists despite ipratropium. 1
- Oral prednisone 30-40 mg daily: For severe paroxysms, use a short finite course (2-3 weeks with taper) after ruling out upper airway cough syndrome, asthma, and GERD. 1
Symptomatic Relief
- Dextromethorphan 60 mg: Maximum cough reflex suppression occurs at this dose (not the subtherapeutic 15-30 mg OTC doses). 4, 2
- Simple home remedies: Honey and lemon mixtures can be effective for benign viral cough. 4, 2
Critical Red Flags Requiring Reassessment
If cough persists beyond 8 weeks, you must consider diagnoses other than postinfectious cough. 1 At that point, evaluate for:
- Upper airway cough syndrome (postnasal drip)
- Asthma
- Gastroesophageal reflux disease
- ACE inhibitor-induced cough
- Tuberculosis (if from high-prevalence area)
- Malignancy 3
Common Pitfalls to Avoid
- Don't prescribe antibiotics for viral postinfectious cough—this provides no benefit and contributes to antibiotic resistance. 1, 2, 3
- Don't assume purulent sputum means bacterial infection—purulence is due to inflammatory cells and sloughed epithelial cells, not bacteria. 1
- Don't use standard OTC dextromethorphan doses (15-30 mg)—these are subtherapeutic; use 60 mg for actual cough suppression. 4
- Don't prescribe codeine or pholcodine—they have no greater efficacy than dextromethorphan but significantly more adverse effects (drowsiness, nausea, constipation, physical dependence). 4