Causes of dry cough
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Causes of Dry Cough: An Overview
Dry cough, characterized by the absence of mucus production, is a common symptom that can arise from various underlying conditions. Understanding the potential causes is crucial for effective diagnosis and treatment. This article synthesizes findings from multiple research studies to provide a comprehensive overview of the causes of dry cough.
Acute Viral Respiratory Infections
One of the most prevalent causes of dry cough is acute viral respiratory infections. These infections can lead to airway irritation and inflammation without the production of excessive secretions, typically lasting up to 3-4 weeks. This type of cough is often self-limiting but can be distressing for patients.
Upper Airway Cough Syndrome (UACS)
Upper airway cough syndrome, previously known as post-nasal drip syndrome, is a significant cause of dry cough. It involves the irritation of the upper airways due to mucus drainage from the nasal passages, which can trigger the cough reflex . This condition is often associated with chronic rhinitis and sinusitis.
Asthma and Cough-Variant Asthma
Asthma, particularly cough-variant asthma, is another common cause of dry cough. In this variant, cough is the predominant symptom rather than wheezing or shortness of breath. The cough reflex in these patients may be sensitized due to airway inflammation .
Gastroesophageal Reflux Disease (GERD)
GERD is a well-documented cause of chronic dry cough. The reflux of stomach acids into the esophagus can irritate the airway and trigger a cough reflex. This condition is often diagnosed through a combination of patient history, physical examination, and sometimes pH monitoring .
Drug-Induced Cough
Certain medications, particularly angiotensin-converting enzyme (ACE) inhibitors, are known to cause dry cough in some patients. This side effect is thought to be due to the accumulation of bradykinin and substance P, which can irritate the airways. The incidence of ACE inhibitor-induced cough is reported to be around 3.9%, with higher prevalence in older adults and females.
Inflammatory Conditions and Cytokine Activity
Inflammatory conditions involving neutrophils and cytokines such as TNF-α and IL-8 have been implicated in non-asthmatic chronic dry cough. Elevated levels of these inflammatory markers in the sputum suggest that airway inflammation plays a significant role in the pathogenesis of this type of cough.
Occult Infections
Occult infections, such as filaria, have also been identified as potential causes of chronic dry cough. In a study conducted in Dhaka, a significant proportion of patients with chronic dry cough tested positive for filaria and responded well to antiparasitic treatment.
Other Causes
Other less common causes of dry cough include heart failure, chronic laryngeal allergy, and certain respiratory infections. Each of these conditions requires specific diagnostic approaches and targeted treatments .
Conclusion
Dry cough can result from a variety of underlying conditions, ranging from acute viral infections to chronic inflammatory diseases and medication side effects. Accurate diagnosis through a thorough patient history, physical examination, and appropriate diagnostic tests is essential for effective management. Understanding the diverse etiologies of dry cough can help healthcare providers tailor treatments to address the root cause, thereby improving patient outcomes.
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