What are the management options for a patient presenting with a cough, considering various underlying causes such as viral upper respiratory infection, allergic rhinitis, bacterial infection, asthma, or chronic obstructive pulmonary disease (COPD)?

Management of Cough

Begin with a focused history to determine cough duration (acute <3 weeks, subacute 3-8 weeks, chronic >8 weeks), ACE inhibitor use, smoking status, and presence of life-threatening conditions, as this classification drives the entire management algorithm. 1

Initial Assessment and Red Flags

First, rule out serious illness such as pneumonia or pulmonary embolism before proceeding with algorithmic management of benign causes. 1 Key historical elements include:

• ACE inhibitor use: Stop the medication immediately if present, as this is a common reversible cause 1
• Smoking status: Counsel and assist with cessation, as smoking exacerbates cough 1
• Signs of serious disease: Fever, weight loss, hemoptysis, or recurrent pneumonia warrant chest radiography and potentially CT imaging 2, 3

Note that cough characteristics (timing, quality) have limited diagnostic value and should not guide your workup. 1

Management by Duration

Acute Cough (<3 weeks)

Determine if this represents a serious illness (pneumonia, pulmonary embolism) versus a benign respiratory tract infection or exacerbation of underlying disease (COPD, asthma, bronchiectasis). 1

• For viral upper respiratory infections, treatment is supportive 1
• Obtain chest radiography if pneumonia is suspected based on tachypnea, abnormal lung findings, or hypoxemia 4
• Avoid antibiotics for viral causes 4

Subacute Cough (3-8 weeks)

First determine if this is postinfectious or non-infectious. 1, 4

For postinfectious cough, consider:

• Upper airway cough syndrome (UACS) 1, 4
• Transient bronchial hyperresponsiveness 1
• Asthma 1
• Pertussis 1
• Acute exacerbation of chronic bronchitis 1

For non-infectious subacute cough, manage as chronic cough (see below). 1, 4

Chronic Cough (>8 weeks)

The three most common causes are upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD), accounting for approximately 90% of cases. 1, 2, 3 Non-asthmatic eosinophilic bronchitis (NAEB) is the fourth common cause. 1

Systematic Treatment Algorithm for Chronic Cough

Use sequential and additive empiric therapy because multiple causes frequently coexist. 1

Step 1: Treat UACS First

Begin with a first-generation oral antihistamine/decongestant combination as initial empiric treatment. 1, 4 This addresses the most common cause and has substantial benefit with low-level evidence supporting Grade B recommendation. 1

Step 2: Evaluate and Treat Asthma

If cough persists after UACS treatment, work up asthma next. 1

• Medical history is not reliable for ruling asthma in or out 1
• Perform spirometry; if it doesn't show reversible airflow obstruction, proceed to bronchoprovocation challenge (BPC) 1, 4
• If BPC is unavailable, initiate empiric trial of anti-asthma therapy with inhaled bronchodilators and inhaled corticosteroids 1, 4

Step 3: Evaluate and Treat NAEB

If UACS and asthma have been eliminated or treated without resolution, consider NAEB. 1

• Perform induced sputum test for eosinophils if available 1, 4
• If induced sputum testing cannot be performed, give empiric trial of inhaled corticosteroids 1, 4

Step 4: Evaluate and Treat GERD

After addressing UACS, asthma, and NAEB, systematically direct treatment at GERD. 1 Initiate empiric treatment with proton pump inhibitors in patients with reflux symptoms rather than performing diagnostic testing. 3

Idiopathic Chronic 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

This condition predominantly affects middle-aged women, often starting around menopause, and is associated with:

• Heightened cough reflex 1
• Lymphocytic airway inflammation 1
• Autoimmune disease in up to 30% of cases (particularly hypothyroidism) 1

Treatment options are limited and disappointing, including:

• Dextromethorphan (non-specific antitussive) 1, 5
• Baclofen (weak evidence) 1
• Nebulized local anesthetics (lidocaine, mepivicaine - weak evidence) 1
• Low-dose morphine (recently shown helpful) 1
• Gabapentin or pregabalin for cough hypersensitivity syndrome 2

Special Considerations

Cough in COPD, Pneumonia, and Bronchiectasis

In pneumonia and bronchiectasis, cough clearance is important and suppression is relatively contraindicated. 1 No studies have evaluated effectiveness of specific treatments on cough in COPD itself. 1

When to Escalate

Obtain high-resolution CT scan and consider bronchoscopy if:

• Cough persists despite appropriate sequential treatment 4
• Red flag symptoms are present (fever, weight loss, hemoptysis, recurrent pneumonia) 2
• Chest radiography shows abnormalities 3

Common Pitfalls to Avoid

• Don't rely on cough characteristics (timing, quality) for diagnosis—they have minimal diagnostic value 1, 4
• Don't use antibiotics for viral causes of acute or subacute cough 4
• Don't treat only one cause—give therapy in sequential and additive steps as multiple etiologies frequently coexist 1
• Don't diagnose idiopathic cough prematurely—ensure thorough evaluation and treatment trials first 1
• Don't suppress cough when clearance is important (pneumonia, bronchiectasis) 1