A chronic cough is defined as a cough that persists for more than 8 weeks and is present in more than 40% of the population. A cough is a non-specific reaction to an irritant present in the airways.
The reaction may occur to foreign body present in any part of the airways from the pharynx to lungs. It may also be triggered by inflammatory events in the airways.
Even when a trigger is absent, chronic cough may persist because of the increased sensitivity of the bronchi. The airways, in this case, may be sensitive to exercise, dry cough, cold air, or certain aerosols.
A chronic cough is categorized into:
Chronic dry cough – this cough is persistent but does not produce any mucus and is usually a symptom of viral infection. Chronic dry cough irritates the lungs and throat and causes quiet a discomfort for the person.
Chronic wet cough – chronic wet cough is characterized by the production of sputum. It may indicate bacterial infection or fluid accumulation in lungs.
A stress cough – this type of a chronic cough is characterized by reflexive spasm of the airways caused by stress. This condition is not related to any stress and does not produce phlegm.
A barking sound for a cough is associated with croup or any other kind of viral infections. The barking sound is produced by swelling in the windpipe. Serious, contagious infection, called pertussis, produces a whooping sound for a cough. It is a respiratory disease that is potentially life threatening for children under one year.
Some of the common causes of a chronic cough are cigarette smoking, asthma, gastroesophageal reflux disease (GERD), postnasal drips, and sinus problems. The most common cause for a persistent cough is smoking.
A chronic cough is a very common symptom for people suffering from asthma, a respiratory disease. Reflux of food contents back into the esophagus is characteristic of GERD. In some cases, the refluxed food may be aspirated into the lungs, causing chronic cough.
Infections like bronchitis and pneumonia may also result in a chronic cough. A whooping cough is caused by the infection of bacteria, Bordetella pertussis. In children, chronic cough may be caused by obstruction of airways, allergies, and asthma.
Certain medications are also implicated in the development of a chronic cough. This includes ACE inhibitors and medications used in the treatment of high blood pressure. Other causes of the condition include tumors, sarcoidosis, congestive heart failure, and chronic obstructive pulmonary disease (COPD).
Treatment of a chronic cough varies with the cause of a persistent cough. Over-the-counter cough medications and lozenges are known to give relief from a cough. In severe cases, cough suppressants like codeine are recommended.
Asthma is treated with bronchodilators and inhalation of steroids. GERD is treated with medications like famotidine, cimetidine, ranitidine, omeprazole and lansoprazole. Decongestants, pseudoephedrine, and antihistamines are useful in relieving symptoms of sinus problems and post nasal drip.
Inhaled nasal steroids are indicated in the control of rhinitis. Nasal inhalers containing ipratropium bromide are used to provide relief in postnasal drip, one of the causes of a chronic cough.
A persistent cough indicates a problem that needs treatment. A chronic cough may be caused by multiple causes, and in some cases, more than one cause may be involved in the development of a persistent cough.
The most common causes of a chronic cough are:
Postnasal drip – postnasal drip refers to the condition in which extra mucus drips down the back of the throat. This causes irritation that triggers a cough. It is also referred to as upper airway cough syndrome.
Asthma – this is one of the most common causes of a chronic cough, next only to smoking. This disease of the airways leads to wheezing and breathlessness as the common symptoms. Cough-variant asthma, a type of asthma has a chronic cough as the only symptom of the condition. Symptoms of asthma can be worsened by triggers including cold conditions, pollen, smoke, and other irritants.
Gastroesophageal reflux disease – this condition is characterized by the reflux of stomach contents into the esophagus and throat. This reflux may irritate the airways, leading to a chronic cough. Coughing may worsen the symptoms of GERD, and the cycle continues.
Infections – infections of the upper respiratory tract are often characterized by a cough. A cough may persist even after the infection is resolved completely. A pertussis or whooping cough is a cause of a chronic cough in adults. In children infection by Bordetella pertussis causes whooping cough, and is a serious condition that requires immediate medical attention.
Certain medications – angiotensin-converting enzyme (ACE) inhibitors are commonly indicated in the treatment of high blood pressure and heart failure. These medications are known to cause a chronic cough in some people.
Chronic bronchitis – inflammation of the bronchial tubes is known as bronchitis, and is commonly seen in smokers. Chronic bronchitis causes a wet cough and is often categorized as a part of smoking-related lung diseases. Chronic obstructive pulmonary disease (COPD) is also a part of this spectrum and often coexists with bronchitis.
A chronic cough may also be caused by:
Aspiration of food into the airways.
Presence of foreign bodies in the airways, especially in children
Bronchiectasis – a condition characterized by abnormally widened airways, leading to a persistent cough
Bronchiolitis – bronchiolitis is a mild form of respiratory tract infection. It is characterized by cold-like symptoms, including a cough.
Cystic fibrosis – this is a serious, long-term condition that affects different organs including lungs. When affected, it may result in a chronic cough.
Lung cancer – in some rare cases, lung cancer may be a cause of a chronic cough in some people.
Nonasthmatic eosinophilic bronchitis – this is a condition characterized by inflammation of the airways, but the cause in not related to asthma.
Sarcoidosis – in this condition, inflammatory cells get collected in the lungs, leading to continuous irritation.
Other causes include interstitial lung disease, psychogenic conditions like stress, tuberculosis, and congestive heart failure. Many heart diseases may also lead to a chronic cough, as fluid accumulation in lungs is common during heart diseases.
Breathing difficulty, wheezing, and other symptoms that resemble asthma are common in heart diseases. A cough, when present is usually a productive cough and may worsen during sleep or while lying down.
3 Diagnosis and Treatment
Diagnosis of the cause of a cough is based on symptoms and also on the basis of information on duration of a cough, accompanying symptoms, activities that worsen or improve a cough, and the time of day during which a cough worsens.
Medical history and physical examination also help in identifying the underlying cause of a cough. Some common questions, the responses to which help in diagnosis include other medical conditions, the presence of heartburn, any recent infections, exposure to smoke, air pollution and dust.
Further diagnostic tests and investigations are based on the suspected cause of a cough. For example, the pH probe is often suggested for people with symptoms of GERD. Some other common tests used in confirmatory diagnosis include analysis of mucus from nasal cavity and throat.
This helps in the identification of the causative organism. A chest x-ray is helpful in diagnosing lung conditions like pneumonia. Lung functions tests are non-invasive tests recommended to diagnose asthma and other lung conditions.
In this test, the amount of air that is inhaled and exhaled is measured. It gives an indication of how well oxygen is delivered to different organs. In some cases, an asthma challenge test will be recommended, in which the pattern of breathing before and after inhaling methacholine drug is observed. Sinus infection is assessed using x-rays in some cases.
If the normal tests do not reveal the possible cause of a chronic cough, scope tests are suggested. In this test, a thin flexible tube, with attached camera, is inserted into the airways to observe the lungs and airways. The tube, known as a bronchoscope, aids to look out for abnormalities if any. It also helps in the collection of cell samples for biopsy.
A chronic cough caused by smoking, irritants, and allergies is controlled by preventing exposure to the causative substance. Treatment for lung diseases is usually multiple and long-term to alleviate the symptoms.
Improvement of the condition is often gradual and may take several days to weeks to note the same. Stopping the medication or reducing the dose of medication that causes a cough is one of the most important steps in reducing cough caused by medications.
Controlling GERD using medications help to alleviate a chronic cough. Antihistamines, glucocorticoids, and decongestants are indicated in the control of allergies and postnasal drip. Acid blockers help to control GERD, one of the causes of a chronic cough.
Cough suppressants are usually suggested if a cough is causing serious problems like disturbing sleep or normal activities. In addition to medications, it may also need dietary changes.
A cough can be avoided by simple preventive measures too. This includes quitting smoking and some dietary changes.
Quitting smoking – smoking is one of the most common causes of a chronic cough. Quitting smoking reduces the risk of common cold and flu, two other causes of a cough.
Dietary changes – healthy diet rich in flavonoids and fiber reduces the chances of developing a chronic cough.
Keeping away from people who have contagious diseases reduces the risk of conditions that cause a cough. Keeping the existing medical conditions, like asthma and GERD, under control helps to prevent chances of a cough. Once managed, cough reduces considerably.
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