Management of Prolonged Cough
A systematic diagnostic and treatment approach targeting the four most common causes—upper airway cough syndrome (UACS), asthma, gastroesophageal reflux disease (GERD), and nonasthmatic eosinophilic bronchitis—will resolve approximately 90% of chronic cough cases in adults when treatments are applied sequentially and additively. 1, 2, 3
Initial Assessment and Red Flag Identification
Begin by determining cough duration, as this drives the entire management algorithm. Chronic cough is defined as lasting longer than 8 weeks in adults. 2, 3
Critical red flags requiring immediate chest radiography and advanced evaluation include: 4, 2
- Hemoptysis of any amount
- Unexplained weight loss
- Fever persisting beyond typical viral illness
- Night sweats
- Dyspnea or tachypnea at rest
- Abnormal lung examination findings (crackles, clubbing, pleural effusion)
Immediately discontinue ACE inhibitors if the patient is taking them, as these cause cough in a significant proportion of patients through heightened cough reflex sensitivity. The cough typically resolves within 26 days of cessation, though it may take up to 40 weeks in some cases. 1, 2
Assess smoking status and initiate cessation counseling, as smokers with persistent cough are at risk of developing COPD, and productive cough in established COPD predicts lung function decline. 1, 2
Baseline Investigations
Obtain chest radiography in all patients with chronic cough to exclude pneumonia, lung cancer, bronchiectasis, tuberculosis, and other structural lung diseases. 1, 2, 5
Order spirometry or bronchoprovocation challenge if asthma is suspected, as medical history alone is unreliable for ruling asthma in or out. 2, 5
Sequential and Additive Treatment Algorithm
The key principle is that chronic cough is frequently multifactorial, and the cough will not resolve until all contributing causes have been effectively treated. 6, 2 When partial improvement occurs with one treatment, continue that therapy and add the next intervention rather than stopping and switching. 6
Step 1: Treat Upper Airway Cough Syndrome (UACS) First
Initiate a first-generation oral antihistamine-decongestant combination (such as brompheniramine/pseudoephedrine or chlorpheniramine/phenylephrine) plus an intranasal corticosteroid spray (fluticasone or mometasone). 6, 2
Expected response time: Days to 1-2 weeks. 6
UACS is one of the most common causes of chronic cough and may present without obvious postnasal drip symptoms on examination. 1, 2
Step 2: Evaluate and Treat Asthma
If cough persists after UACS treatment, perform spirometry or bronchoprovocation challenge to confirm asthma, then initiate inhaled corticosteroids (fluticasone 220 mcg or budesonide 360 mcg twice daily) and beta-agonists. 6, 2
Expected response time: Up to 8 weeks. 6
Cough-variant asthma may present without wheezing or dyspnea, making empiric treatment trials necessary when spirometry is normal but clinical suspicion remains high. 1, 2
Step 3: Treat GERD
If cough persists despite UACS and asthma treatment, initiate high-dose PPI therapy (omeprazole 40 mg twice daily) with dietary modifications, even in the absence of typical GI symptoms. 6, 2
Expected response time: 2 weeks to several months. 6
GERD-related cough may occur without heartburn or regurgitation, and the prolonged response time requires patience before declaring treatment failure. 6, 2
Step 4: Consider Nonasthmatic Eosinophilic Bronchitis
If the above treatments fail, consider empiric inhaled corticosteroid trial for nonasthmatic eosinophilic bronchitis, which presents with normal spirometry and negative bronchoprovocation but responds to inhaled corticosteroids. 1, 3
Special Considerations for Specific Respiratory Conditions
Chronic Bronchitis and COPD
The most effective treatment is avoidance of respiratory irritants, particularly smoking cessation. 1 In the Lung Health Study, 90% of patients who stopped smoking and had chronic cough at baseline reported no cough by the end of the 5-year study period. 1
Cough suppression is relatively contraindicated when cough clearance is important for mucus expectoration. 1, 2
If patients develop sudden deterioration with increased cough, sputum production, sputum purulence, and/or shortness of breath (often preceded by upper respiratory infection symptoms), consider acute exacerbation of chronic bronchitis. 1
Pneumonia
Cough suppression is relatively contraindicated as cough clearance is essential for recovery. 1, 2
Suspect pneumonia in patients with tachypnea, tachycardia, dyspnea, or lung findings suggestive of consolidation, and obtain chest radiography. 7
Bronchiectasis
Although typically associated with productive cough, "dry" bronchiectasis can cause persistent cough. The prevalence among specialist cough clinic patients is approximately 4%. 1
Cough suppression is relatively contraindicated as airway clearance is critical. 1, 2
Coarse crackles on examination suggest this diagnosis, and high-resolution CT is the gold standard for confirmation. 1, 4
Lung Cancer
Cough is the fourth most common presenting feature of lung cancer and contributes significantly to impaired quality of life. 1
The combination of persistent cough with weight loss, hemoptysis, or smoking history mandates complete evaluation including chest radiography and CT if radiography is equivocal. 4
Radiotherapy and both opioid and non-opioid antitussives have been recommended for symptomatic management. 1
Pertussis Infection
Consider pertussis in patients with cough persisting beyond 2 weeks accompanied by paroxysmal cough, whooping cough, post-tussive emesis, or recent pertussis exposure. 1, 7
In prospective studies, 10% of chronic cough cases had nasal swabs positive for Bordetella. 1
Postinfectious Cough (Subacute: 3-8 Weeks)
If cough follows a recent upper respiratory infection and persists 3-8 weeks, diagnose postinfectious cough based on timeline (initial URI symptoms for 3 days, followed by cough for 7 days, persisting 3-8 weeks) and clinical presentation (non-purulent sputum, no fever, clear lungs except transient wheezes). 6
Antibiotics are explicitly contraindicated as the cause is not bacterial infection. 6
Treatment algorithm for postinfectious cough: 6
- Supportive care with guaifenesin (200-400 mg every 4 hours, up to 6 times daily) for initial 1-2 weeks
- Inhaled ipratropium bromide (2-3 puffs four times daily) if symptoms persist or worsen after 1-2 weeks
- Inhaled corticosteroids (fluticasone 220 mcg or budesonide 360 mcg twice daily) if quality of life remains significantly affected after ipratropium
- Oral prednisone (30-40 mg daily for 5-10 days) reserved only for severe paroxysms significantly impairing quality of life after other causes have been ruled out
Refractory Chronic Cough and Idiopathic Cough
Idiopathic cough is a diagnosis of exclusion that should not be made until thorough diagnostic evaluation is performed, specific treatment has failed, and uncommon causes have been ruled out. 1, 2
If all empiric therapies fail and chest X-ray is normal, consider high-resolution CT chest and bronchoscopy, particularly if physical exam reveals crackles, clubbing, or other concerning findings. 6, 2
Treatment options for idiopathic chronic cough include: 1, 2
- Dextromethorphan (non-specific antitussive)
- Baclofen (weak evidence)
- Nebulized local anesthetics (lidocaine, mepivicaine)
- Low-dose morphine (recently shown helpful)
- Gabapentin or pregabalin (for cough hypersensitivity syndrome)
- Speech therapy trial
Referral to pulmonologist or otolaryngologist is warranted for refractory cases. 3, 8
Common Pitfalls to Avoid
Do not rely on cough characteristics (timing, quality, wet vs. dry) for diagnosis—they have minimal diagnostic value. 2
Do not treat only one cause—therapy must be given in sequential and additive steps as multiple etiologies frequently coexist. 6, 2
Do not diagnose idiopathic cough prematurely—ensure thorough evaluation and adequate treatment trials (with appropriate duration for response) before concluding treatments have failed. 1, 2
Do not suppress cough when clearance is important (pneumonia, bronchiectasis, productive COPD). 1, 2
Do not prescribe antibiotics for viral causes of acute or postinfectious cough—they provide minimal benefit (reducing cough by only half a day) and cause adverse effects including allergic reactions, nausea, vomiting, and C. difficile infection. 6, 7
Green or colored sputum does not indicate bacterial infection—most short-term coughs are viral even when producing colored phlegm. 6