Cough: Symptoms, Causes and Treatment

Cough is one of the most common reasons people seek medical care, affecting individuals of all ages and backgrounds. While often a temporary annoyance, a cough can sometimes signal an underlying health issue that requires attention. Understanding the symptoms, causes, and treatment options for cough is crucial for both patients and healthcare professionals. In this article, we’ll explore the current evidence on cough, drawing from leading research and clinical guidelines to provide a comprehensive overview.

Symptoms of Cough

Cough presents in a variety of forms, ranging from an occasional throat clearing to persistent, disruptive episodes that can severely affect daily life. The way a cough manifests—its frequency, intensity, triggers, and associated sensations—can provide valuable clues about its underlying cause. Recognizing these symptoms is the first step towards effective diagnosis and management.

Feature	Description	Additional Notes	Source(s)
Frequency	Can be acute, subacute, or chronic	Acute (<3 weeks), subacute (3–8 weeks), chronic (>8 weeks)	1 2
Intensity	Varies from mild to severe	Can be measured using visual analog scales	2 4
Triggers	Environmental or specific irritants	Perfumes, cold air, smoke, etc.	3 13
Sequelae	Associated features or complications	Fatigue, sore throat, chest pain	2 4 5

Table 1: Key Symptoms of Cough

The Types and Patterns of Cough

A cough can be classified based on its duration:

• Acute Cough: Lasts less than 3 weeks, often associated with infections like the common cold.
• Subacute Cough: Persists for 3 to 8 weeks, sometimes following a respiratory infection.
• Chronic Cough: Lasts more than 8 weeks and is often a sign of underlying disease 1 13.

Severity and Impact

Severity varies widely:

• Patients may experience anything from an occasional cough to relentless, debilitating episodes.
• Severity can be quantified using patient-reported outcome measures, such as the Visual Analog Scale (VAS), especially in research or clinical trials 2 4.
• Chronic cough can severely impact quality of life, causing embarrassment, fatigue, disturbed sleep, and even incontinence 2 4.

Triggers and Sensations

Cough can be triggered or worsened by:

• Environmental factors: cold air, smoke, strong smells (perfumes, bleach) 3 13.
• Physical exertion or changes in body position.
• Underlying airway sensitivity, now understood as "cough hypersensitivity syndrome"—a condition where nerves in the airway are overly responsive 13.

Associated Features and Complications

Beyond the act of coughing itself, people may experience:

• Sore throat, chest pain, or hoarseness.
• Shortness of breath or wheezing, especially if the cough is linked to asthma or COPD 5.
• Sequelae such as vomiting, headaches, or syncope (fainting) in severe cases 2.

Understanding the specific symptoms and patterns of a cough provides important direction for diagnosis and treatment.

Causes of Cough

Cough is not a disease in itself but a symptom with a wide range of potential causes. These causes can be broadly grouped by duration, underlying medical conditions, and environmental factors. Identifying the source of a cough is key to effective treatment.

Category	Common Causes	Notable Features / Notes	Source(s)
Acute	Viral infections, allergies, irritants	Often self-limiting	1 11 12
Chronic	Asthma, upper airway cough syndrome (UACS), GERD, eosinophilic bronchitis, COPD	May involve one or multiple conditions	6 7 8 9 13
Environmental	Smoking, pollution, occupational exposures	Risk increases with exposure	9 4
Other/Complex	Interstitial lung disease, bronchiectasis, idiopathic cough	May require specialist evaluation	14 9 7

Table 2: Common Causes of Cough

Acute vs. Chronic Cough

• Acute Cough: Most often due to viral infections (e.g., the common cold, influenza), allergies, or exposure to irritants. Acute cough is typically self-limited and resolves as the underlying cause improves 1 11 12.
• Chronic Cough: Defined as lasting more than 8 weeks. Chronic cough requires a thorough evaluation to identify and address the underlying cause 1 6 7 8 9.

The "Pathogenic Triad" in Chronic Cough

Research highlights three main culprits—sometimes called the "pathogenic triad":

• Asthma: Can present primarily as cough, even without classic wheezing. Cough variant asthma is especially common 7 13.
• Upper Airway Cough Syndrome (UACS): Formerly known as postnasal drip syndrome, this covers coughs associated with nasal or sinus conditions, including allergic rhinitis, sinusitis, and non-allergic rhinitis. The term UACS is now preferred 8.
• Gastroesophageal Reflux Disease (GERD): Acid or non-acid reflux can irritate the airway and trigger cough. GERD may mimic or coexist with other causes 7 8 9.

These three conditions account for the vast majority of chronic cough cases in adults, either individually or in combination 7 8.

Other Important and Overlapping Causes

• Eosinophilic Bronchitis: Characterized by airway inflammation (eosinophilia) without airway narrowing seen in asthma. It responds well to inhaled corticosteroids 6 13.
• Chronic Obstructive Pulmonary Disease (COPD): Cough, often with sputum production, is a cardinal feature and is associated with worse outcomes 5 9.
• Environmental Factors: Smoking, secondhand smoke, and air pollution contribute to both acute and chronic cough, especially in susceptible individuals 9.
• Infections: Persistent cough after viral infections is common and may last several weeks.
• Bronchiectasis and Interstitial Lung Diseases: Less common but important, these conditions are characterized by chronic airway or lung tissue changes 7 14.
• Idiopathic (Unexplained) Cough: In some cases, no clear cause can be identified, leading to a diagnosis of unexplained chronic cough 10 13 14.

Special Considerations

• COVID-19: Cough is a predominant symptom of COVID-19, especially with the Omicron variant. Certain groups—women, individuals with asthma, chronic cough, GERD, heart disease, or diabetes—are at increased risk of severe or persistent cough 4.
• Children: Causes of cough in children differ from adults; persistent bacterial bronchitis and foreign body aspiration are common in young children 13.
• Multiple Causes: Studies show that more than half of chronic cough cases involve more than one underlying condition, making thorough evaluation essential 7.

Treatment of Cough

Treating a cough effectively depends on identifying and addressing its underlying cause. While many coughs resolve on their own, persistent or severe coughs often require targeted therapy. Recent guidelines emphasize a systematic, patient-centered approach, integrating both traditional and newer treatment strategies.

Approach	Description	Key Points / Options	Source(s)
Treat underlying	Address primary cause (asthma, UACS, GERD, etc.)	Most effective for chronic cough	1 7 8 9 12
Symptomatic Relief	Antitussives, neuromodulators, speech therapy	For refractory or unexplained cough	10 13 14
Non-pharmacological	Speech pathology/cough suppression therapy	Evidence supports benefit	10 13 14
Special Populations	Children, ILD, idiopathic cough	Requires tailored approach	13 14

Table 3: Overview of Cough Treatments

Stepwise Approach to Management

• Identify and Treat the Cause: The cornerstone of cough management is identifying the underlying cause and treating it directly.
  • Asthma: Inhaled corticosteroids and bronchodilators.
  • UACS: Nasal steroids, antihistamines, or treatment of sinus disease.
  • GERD: Lifestyle changes, acid-suppressing medications if reflux is present 7 8 9 12.
  • Eosinophilic Bronchitis: Inhaled corticosteroids are highly effective 6 13.
  • COPD: Smoking cessation, inhaled therapies, and pulmonary rehabilitation 5 9.

Symptomatic and Adjunctive Therapies

• Antitussives: Codeine and other opiates can suppress cough but are reserved for select cases due to side effects and dependency risk. Low-dose morphine may be effective for refractory chronic cough 13 14.
• Neuromodulators: Medications like gabapentin and pregabalin target cough hypersensitivity and can reduce cough severity in unexplained chronic cough. Gabapentin is specifically recommended in guidelines for refractory cough 10 13 14.
• Speech and Cough Suppression Therapy: Specialist-led interventions to teach patients techniques to suppress or control cough have proven benefits, especially for unexplained or refractory cough 10 13 14.
• Other Therapies: Emerging treatments targeting nerve pathways (such as P2X3 receptor antagonists) are under investigation 13.

Special Situations

• Unexplained Chronic Cough (UCC): When no cause is identified after thorough workup, neuromodulators and speech pathology-based therapy are recommended. Inhaled corticosteroids and acid suppressants are not effective unless features of asthma or GERD are present 10 13.
• Interstitial Lung Disease (ILD): Limited options; gabapentin, speech therapy, and opiates may be considered for refractory cases 14.
• Children: A separate diagnostic and management approach is required. Persistent bacterial bronchitis should be considered and treated with antibiotics when appropriate 13.
• COVID-19: Management focuses on symptomatic relief unless there is evidence of bacterial infection or other treatable causes 4.

General Principles

• Avoid Overuse of Cough Suppressants: Routine use, especially in children, is discouraged due to lack of benefit and potential harm.
• Multifactorial Causes: Address all potential contributors, as more than one condition may be at play 7.
• Patient-Centered Care: Consider the impact on quality of life and tailor management plans to individual needs and preferences 2 10.

Conclusion

Cough is a complex and multifaceted symptom that can range from a benign annoyance to a sign of serious disease. Understanding its symptoms, causes, and evidence-based treatment options is essential for effective management.

Key Takeaways:

• Cough varies in frequency, intensity, triggers, and associated features; chronic cough can have a profound impact on quality of life 2 4.
• Most chronic coughs in adults are due to asthma, upper airway cough syndrome (UACS), or GERD, with many cases having multiple contributing factors 7 8.
• Diagnosis should be systematic and thorough, with treatment focused first on the underlying cause 1 9 12.
• For unexplained or refractory cough, neuromodulators like gabapentin and speech pathology interventions offer effective options; low-dose morphine is a consideration for select patients 10 13 14.
• Management strategies should be tailored to special populations, such as children and individuals with interstitial lung disease 13 14.
• Ongoing research continues to refine our understanding of cough and to develop better treatments, especially for those whose symptoms persist despite standard therapies 13.

By applying a patient-centered, evidence-based approach, clinicians can help most individuals with cough achieve relief and improve their quality of life.