Coughs Overview
A cough is an action the body takes to get rid of substances that are irritating to the air passages, which carry the air a person breathes in from the nose and mouth to the lungs. A cough occurs when cells along the air passages get irritated and trigger a chain of events. The result is air in the lungs is forced out under high pressure. A person can choose to cough (a voluntary process), or the body may cough on its own (an involuntary process).
Causes of Coughs
Acute coughs can be divided into infectious (caused by an infection) and noninfectious causes.
- Infectious causes of acute cough include viral upper respiratory infections (the common cold), sinus infections, acute bronchitis, pneumonia, and whooping cough.
- Noninfectious causes of cough include flare-ups of chronic conditions such as chronic bronchitis, emphysema, asthma, and environmental allergies.
The easiest way to simplify the causes of chronic cough is to divide them into their locations with respect to the lungs. The categories are environmental irritants, conditions within the lungs, conditions along the passages that transmit air from the lungs to the environment, conditions within the chest cavity but outside of the lungs, and digestive causes.
- Any environmental substance that irritates the air passages or the lungs is capable of producing a chronic cough with continued exposure. Cigarette smoke is the most common cause of chronic cough. Other cough-producing irritants include dusts, pollens, pet dander, particulate matter, industrial chemicals and pollution, cigar and pipe smoke, and low environmental humidity.
- Within the lungs both common and uncommon conditions cause chronic cough. Common causes include asthma, emphysema, and chronic bronchitis. Less common causes of lung-induced chronic cough include cancer,sarcoidosis, diseases of the lung tissue, and congestive heart failure with chronic fluid build-up in the lungs.
- The passages that connect the lungs to the external environment are known as the upper respiratory tract. Chronic sinus infections, chronic postnasal drip, diseases of the external ear, infections of the throat, and use of ACE inhibitor medications for high blood pressure have all been implicated in chronic cough.
- In addition to disease processes within the lung and air passages, diseases elsewhere within the chest cavity may also be responsible for chronic cough. Conditions within the chest known to cause chronic cough include cancer, unusual growth of a lymph node, and an abnormal enlargement of the aorta, the main blood vessel leaving the heart.
- An often-overlooked cause of the chronic cough is gastroesophageal reflux (GERD). GERD occurs when acid from the stomach travels up the esophagus. This abnormal condition can cause irritation of the esophagus and larynx resulting in the reflex production of a cough.
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