What could be causing my 4-week cough, trouble breathing, chest pain when breathing, and sore throat?

Evaluation and Management of 4-Week Cough with Respiratory Symptoms

You have a subacute cough (3-8 weeks duration) that requires immediate evaluation for pertussis and other serious conditions, followed by targeted treatment based on the most likely causes. 1

Immediate Red Flag Assessment

Your symptoms require urgent evaluation for potentially serious conditions:

• Trouble breathing and chest pain when breathing are red flags that necessitate immediate assessment to rule out pneumonia, pulmonary embolism, or other life-threatening conditions 1
• Hemoptysis (coughing blood), if present, requires immediate evaluation 1
• Prominent dyspnea (shortness of breath) at rest is a red flag requiring urgent workup 1

Most Likely Diagnosis: Pertussis

Given your 4-week cough with trouble breathing and chest pain, pertussis (whooping cough) must be considered and treated immediately without waiting for laboratory confirmation. 1, 2, 3

Why Pertussis is the Primary Concern:

• Any cough lasting ≥2 weeks with respiratory symptoms should be considered pertussis until proven otherwise 1, 2, 3
• The diagnosis should be made clinically when cough has persisted for >2 weeks without another apparent cause 1
• Look for paroxysmal coughing fits, post-tussive vomiting, or inspiratory whooping sound - though these may not always be present 1, 2

Immediate Treatment Protocol:

• Start azithromycin 500 mg once daily for 3-5 days immediately without waiting for test results 2, 3, 4
• Alternative: Erythromycin 1-2 g/day for 2 weeks or clarithromycin 3
• Isolate yourself for 5 days from the start of antibiotic treatment to prevent transmission 1, 2, 3
• Early treatment within the first 2 weeks decreases coughing paroxysms and prevents spread 1, 2, 3

Diagnostic Confirmation:

• Obtain nasopharyngeal aspirate or Dacron swab for B. pertussis culture - this is the only definitive diagnostic test 1, 3
• Do not delay treatment waiting for culture results - treatment effectiveness decreases with delay 2, 3

Alternative Diagnoses for Subacute Cough (3-8 Weeks)

If pertussis is ruled out, the most common causes of subacute cough are: 1

1. Post-Infectious Cough (48.4% of cases)

• Most common cause of subacute cough 1
• Treatment approach:
  • First-line: Inhaled ipratropium to attenuate cough 1, 2, 5
  • Second-line: Inhaled corticosteroids if cough persists despite ipratropium and adversely affects quality of life 1
  • For severe paroxysms: Prednisone 30-40 mg daily for a short period after ruling out other causes 1, 2, 5
  • Antibiotics have no role if bacterial infection is not confirmed 1, 3

2. Upper Airway Cough Syndrome/Post-Nasal Drip (33.2% of cases)

• Second most common cause with sore throat being a key symptom 1
• Treat empirically for rhinosinus conditions 1

3. Asthma (15.8% of cases)

• Consider if cough worsens at night or with cold/exercise exposure 1
• Spirometry may show transient bronchial hyperresponsiveness 1
• Trial of bronchodilator treatment 1

4. Exacerbations of Underlying Disease (COPD)

• Consider if you are a smoker 1

Essential Diagnostic Workup

Obtain chest radiograph immediately to rule out pneumonia, given your trouble breathing and chest pain 1

Pneumonia Must Be Excluded:

• Check vital signs: heart rate ≥100 bpm, respiratory rate ≥24 breaths/min, or temperature ≥38°C suggest pneumonia 1
• Focal consolidation on chest exam (rales, egophony, fremitus) indicates pneumonia 1
• If pneumonia is present, different treatment is required 1

Symptomatic Treatment While Awaiting Diagnosis

For Cough Suppression:

• Dextromethorphan 60 mg (not over-the-counter doses which are subtherapeutic) provides maximum cough reflex suppression 2, 5
• Avoid codeine - it has no greater efficacy than dextromethorphan but worse side effects 2, 5
• For nighttime cough: First-generation sedating antihistamines 5
• Simple remedies: Honey and lemon may be as effective as pharmacological treatments 5

For Sore Throat:

• Symptomatic relief with analgesics and throat lozenges while addressing underlying cause

Critical Follow-Up Timeline

• Follow up within 4-6 weeks after initial evaluation 1
• If cough persists beyond 8 weeks, it becomes chronic cough requiring full workup for upper airway cough syndrome, asthma, gastroesophageal reflux disease, and nonasthmatic eosinophilic bronchitis 1, 6

Common Pitfalls to Avoid

• Do not delay pertussis treatment waiting for laboratory confirmation - this decreases treatment effectiveness 2, 3
• Do not use antibiotics indiscriminately for viral post-infectious cough - they provide no benefit 1, 3
• Do not use subtherapeutic doses of dextromethorphan - over-the-counter doses are insufficient; 60 mg is needed 2, 5
• Do not forget isolation precautions if pertussis is diagnosed - you remain contagious until 5 days after starting antibiotics 1, 2, 3
• Do not dismiss trouble breathing and chest pain - these require urgent evaluation for pneumonia and other serious conditions 1