Cough MedicalEdit
Cough is one of the most frequent symptoms prompting medical evaluation and can reflect a wide spectrum of conditions, from self-limited viral infections to chronic diseases of the airways and chest. From a clinical perspective, the goal is to distinguish benign etiologies from conditions that require targeted treatment or further investigation, while avoiding unnecessary interventions. The medical approach emphasizes understanding the underlying cause, using evidence-based therapies, and considering patient safety and quality of life in management decisions.
Causes
Coughs are typically categorized by duration and underlying mechanism. Understanding the duration helps narrow the differential diagnosis and guides testing and treatment.
Acute cough (about 0–3 weeks)
- Most often caused by viral upper respiratory infections such as the common cold common cold or influenza influenza.
- Acute bronchitis, typically viral, can follow a viral URI and present with productive or nonproductive cough.
- Less commonly, bacterial pneumonia or pertussis can present with cough, particularly if fever, focal findings, or systemic symptoms are present.
Subacute cough (about 3–8 weeks)
- Post-infectious cough can persist after resolution of the initial illness.
- Cough-variant asthma or evolving asthma can present with cough without classic wheeze.
Chronic cough (more than 8 weeks)
- The most common chronic etiologies include postnasal drip from chronic rhinosinusitis or allergies, asthma, and gastroesophageal reflux disease (GERD) GERD.
- Smoking-related cough and chronic obstructive pulmonary disease (COPD) COPD are important causes in appropriate patients.
- Less common but important causes include bronchiectasis, chronic infections, or medications such as ACE inhibitors ACE inhibitors.
Common etiologies and related concepts to explore during evaluation: - Postnasal drip and sinus disease postnasal drip and sinusitis. - Airway hyperreactivity and asthma asthma. - Gastroesophageal reflux presenting as cough GERD. - Smoking-related irritation and COPD smoking as a risk factor. - Medication-induced cough, notably ACE inhibitors ACE inhibitors. - Less frequently, structural lung disease, immune deficiency, or chronic infections.
Pathophysiology
Cough results from the cough reflex arc, a coordinated interaction between airway receptors, sensory nerves (notably the vagus nerve), and brainstem processing centers. Irritants or inflammatory mediators stimulate airway receptors, triggering a reflex that ends in a forceful expiratory effort. The reflex can be triggered by a diverse set of stimuli, including viral particles, allergens, refluxate, or environmental irritants. Understanding the reflex helps explain why different conditions produce a similar symptom and why treatment often targets specific triggers or underlying diseases rather than the cough itself alone.
Evaluation
A thoughtful history and physical examination are central to assessing a cough. Important elements include: - Duration and pattern of the cough (acute, subacute, chronic) and any associated symptoms (fever, weight loss, night sweats, hemoptysis, shortness of breath). - Exposure history (smoking, occupational or environmental irritants, contact with ill persons). - Associated conditions (nasal congestion, sinus symptoms, heartburn, wheeze, exercise intolerance). - Medication review, particularly use of ACE inhibitors. - Red flags suggesting more serious disease (eg, coughing up blood, unexplained weight loss, persistent fever, new focal lung findings).
Key diagnostic steps may include: - Physical examination focusing on the chest, throat, and nasal passages. - Chest radiography in cases with red flags, persistent cough, or abnormal lung findings. - Spirometry with bronchodilator testing when asthma or COPD is suspected. - Consideration of focused testing (pneumonia workup, CT imaging, or specialty referrals) if initial evaluation is unrevealing or red flags are present.
Treatment
Treatment depends on the identified or suspected underlying cause, with an emphasis on safety and evidence-based practice.
General approaches
- Hydration and humidified air can soothe throat irritation.
- Honey may provide symptomatic relief for adults and children over one year old in some settings (not suitable for infants under one year).
- Addressing environmental triggers (smoke, pollutants, allergens) can reduce cough frequency in sensitive patients.
- Vaccinations against influenza and pneumococcus can reduce the incidence and severity of infectious causes of cough influenza.
Pharmacologic options
- Antitussives (cough suppressants) such as dextromethorphan or benzonatate can lessen cough in many patients, though efficacy varies and these are not appropriate for all etiologies. They should be used judiciously, with attention to age recommendations and potential drug interactions.
- Expectorants like guaifenesin aim to loosen secretions, though evidence for edema-free improvement is variable; they may be reasonable in productive coughs to aid mucus clearance.
- In cases where bacterial infection is suspected or confirmed (eg, pneumonia in certain contexts), antibiotics may be indicated, but broad antibiotic use for uncomplicated acute bronchitis or most viral infections is discouraged due to resistance concerns. Antibiotic stewardship is a central consideration in modern practice.
- Cough syrups containing codeine or other sedatives are regulated differently by jurisdiction; their use is often restricted in children and in patients with certain medical histories due to safety concerns.
Special populations
- Children require careful dosing and consideration of age-appropriate preparations; many guidelines discourage routine use of certain cough medicines in young children due to limited efficacy and safety concerns.
- Smokers and patients with COPD or asthma should have optimized management of their underlying disease, which often reduces cough burden.
Red flags and when to seek further care
- Persistent or worsening symptoms despite initial management.
- New or worsening wheezing, significant shortness of breath, chest pain, fever, or unintentional weight loss.
- Hemoptysis or signs of pneumonia or other serious illness.
Controversies and debates
Medically, several areas of ongoing debate shape how cough is managed in practice: - Antibiotic stewardship and acute cough: Many acute coughs are viral; therefore, antibiotics offer little benefit and contribute to resistance. The controversy centers on when to prescribe antibiotics and how to balance patient expectations with public health considerations. - Efficacy of over-the-counter cough medicines: The value of antitussives and expectorants varies by individual and underlying cause. Critics argue that many products have modest or inconsistent trial results, leading to calls for clearer labeling and more rigorous evaluation. - Pediatric safety of cough remedies: Some cough medicines have restricted use in children due to safety concerns, with debates over appropriate age cutoffs and the need for safer, alternative strategies. - Management of chronic cough etiologies like cough-variant asthma and GERD: There is ongoing discussion about when to treat for reflux or airway sensitivity in patients with chronic cough, and how aggressively to manage coexisting conditions to improve cough outcomes. - Role of nonpharmacologic strategies: There is increasing interest in behavioral and environmental interventions, particularly for chronic cough associated with habit or behavioral components, where nonpharmacologic approaches can be effective and carry minimal risk.