What causes coughing
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Causes of Cough: An Overview
Coughing is a common reflex action that serves to clear the airways of irritants and secretions. It can be triggered by a variety of factors, ranging from infections to environmental irritants. This article synthesizes the key causes of cough based on recent research findings.
Common Causes of Chronic Cough
Upper Airway Cough Syndrome (UACS)
Upper Airway Cough Syndrome (UACS), previously known as postnasal drip syndrome, is a frequent cause of chronic cough. It is often associated with rhinosinus conditions and can occur alone or in combination with other conditions such as asthma and gastroesophageal reflux disease (GERD) 14.
Asthma and Nonasthmatic Eosinophilic Bronchitis (NAEB)
Asthma is another prevalent cause of chronic cough, characterized by airway inflammation and hyperreactivity. Nonasthmatic eosinophilic bronchitis (NAEB) also contributes to chronic cough and is similar to asthma but without the typical asthma symptoms 14.
Gastroesophageal Reflux Disease (GERD)
GERD is a significant contributor to chronic cough, where stomach acid refluxes into the esophagus, irritating the airway and causing a cough reflex. This condition often coexists with UACS and asthma, forming a "pathogenic triad" responsible for the majority of chronic cough cases 14.
Environmental and Occupational Factors
Indoor and Outdoor Pollutants
Environmental factors such as indoor irritants (cigarette smoke, cooking fumes, dust mites) and outdoor pollutants (allergens, industrial emissions) can exacerbate or cause chronic cough. Occupational exposures to irritants and allergens can also lead to conditions like hypersensitivity pneumonitis and occupational asthma, contributing to chronic cough 27.
Sick Building Syndrome
Sick building syndrome, caused by poor indoor air quality, can lead to chronic cough among individuals spending significant time in affected buildings. This syndrome is often linked to indoor pollutants and inadequate ventilation .
Acute Cough and Common Cold
Viral Infections
The common cold, primarily caused by viral infections such as rhinovirus, is the most common cause of acute cough. The cough results from direct irritation of the upper airway structures and can persist even after other cold symptoms have resolved 39.
Postinfectious Cough
Following a viral upper respiratory infection, some individuals develop a postinfectious cough due to an inflammatory response. This subacute or chronic cough can be self-perpetuating if not actively treated .
Specific Pathogens
Whooping Cough (Pertussis)
Whooping cough, caused by Bordetella pertussis, involves bacterial factors like pertussis toxin that induce cough by sensitizing the ion channel TRPV1 on neurons. This leads to the production of bradykinin, a known cough inducer .
Mechanisms of Cough
Sensory and Motor Nerve Involvement
Coughing involves complex interactions between sensory and motor nerves. Irritants stimulate receptors in the vagus nerve, leading to the release of neuropeptides like substance P, which triggers the cough reflex. This reflex involves both central and peripheral pathways, making cough a common symptom in many respiratory disorders .
Inflammatory Responses
Chronic cough can also result from structural and inflammatory changes in the airway mucosa. These changes may either cause the cough or be a response to repetitive coughing, highlighting the need for targeted treatments to desensitize cough pathways .
Conclusion
Coughing is a multifaceted symptom with various underlying causes, including UACS, asthma, GERD, environmental and occupational factors, and specific infections like the common cold and whooping cough. Understanding these causes is crucial for effective diagnosis and treatment, ensuring better management of this common yet complex symptom.
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