A cough in children may be either a normal physiological reflex or due to an underlying cause. In adults with a chronic cough, i.e. a cough longer than 8 weeks, more than 90% of cases are due to
post-nasal drip,
asthma,
eosinophilic bronchitis, and
gastroesophageal reflux disease. In people with a normal chest X-ray, tuberculosis is a rare finding. Pertussis is increasingly being recognised as a cause of troublesome coughing in adults. After a respiratory tract infection has cleared, the person may be left with a
postinfectious cough. This typically is a dry, non-productive cough that produces no
phlegm. Symptoms may include a tightness in the chest, and a tickle in the throat. This cough may often persist for weeks after an illness. The cause of the cough may be inflammation similar to that observed in repetitive stress disorders such as
carpal tunnel syndrome. The repetition of coughing produces inflammation which produces discomfort, which in turn produces more coughing. Postinfectious cough typically does not respond to conventional cough treatments. Medication used for postinfectious coughs may include
ipratropium Inflammation may increase sensitivity to other existing issues such as
allergies, and treatment of other causes of coughs (such as use of an air purifier or allergy medicines) may help speed recovery.
Reactive airway disease When coughing is the only complaint of a person who meets the criteria for asthma (
bronchial hyperresponsiveness and reversibility), this is termed
cough-variant asthma. Atopic cough and
eosinophilic bronchitis are related conditions. Atopic cough occurs in individuals with a
family history of
atopy (an allergic condition), abundant
eosinophils in the sputum, but with normal airway function and responsiveness. Eosinophilic bronchitis is characterized by
eosinophils in sputum and in
bronchoalveolar lavage fluid without airway hyperresponsiveness or an atopic background. This condition responds to treatment with
corticosteroids. Cough can also worsen in an
acute exacerbation of chronic obstructive pulmonary disease. Asthma is a common cause of chronic cough in adults and children. Coughing may be the only symptom the person has from their asthma, or asthma symptoms may also include wheezing, shortness of breath, and a tight feeling in their chest. Depending on how severe the asthma is, it can be treated with bronchodilators (medicine which causes the airways to open up) or inhaled steroids. Treatment of the asthma should make the cough go away.
Chronic bronchitis is defined clinically as a persistent cough that produces sputum (phlegm) and mucus, for at least three months in two consecutive years. Chronic bronchitis is often the cause of "
smoker's cough". The tobacco smoke causes inflammation, secretion of mucus into the airway, and difficulty clearing that mucus out of the airways. Coughing helps clear those secretions out. May be treated by quitting smoking. May also be caused by
pneumoconiosis and long-term fume inhalation.
Gastroesophageal reflux In people with unexplained cough,
gastroesophageal reflux disease should be considered.
Drug-induced cough Drugs used for treatments other than coughs, such as
ACE inhibitors which are often used to treat
high blood pressure, can sometimes cause cough as a side effect, and stopping their use will stop the cough. Beta blockers similarly cause cough as an adverse event.
Neurogenic cough Some cases of chronic cough may be attributed to a sensory neuropathic disorder. Treatment for neurogenic cough may include the use of certain neuralgia medications. Coughing may occur in
tic disorders such as
Tourette syndrome, although it should be distinguished from throat-clearing in this disorder.
Other Cough may also be caused by conditions affecting the lung tissue such as
bronchiectasis,
cystic fibrosis,
interstitial lung diseases and
sarcoidosis. Coughing can also be triggered by
benign or
malignant lung tumors or mediastinal masses. Through irritation of the nerve, diseases of the external auditory canal (wax, for example) can also cause cough. Cardiovascular diseases associated with cough are heart failure, pulmonary infarction and aortic aneurysm. Nocturnal cough is associated with heart failure, as the
left ventricle doesn't effectively pump blood forward, resulting in blood being backed up in the
pulmonary veins, which in turn causing
pulmonary edema and resultant cough. Other causes of nocturnal cough include
asthma,
post-nasal drip and
gastroesophageal reflux disease (GERD). Another cause of cough occurring preferentially in
supine position is recurrent aspiration. Given its irritant nature to mammal tissues,
capsaicin is widely used to determine the cough threshold and as a tussive stimulant in clinical research of cough suppressants. Capsaicin is what makes
chili peppers spicy, and might explain why workers in factories with these fruits can develop a cough. Coughing may also be used for social reasons, and as such is not always involuntary. A voluntary cough, often written as "ahem", can be used to attract attention or express displeasure, as a form of
nonverbal,
paralingual metacommunication.
Airway clearance Coughing, and
huffing are important ways of removing mucus as
sputum in many conditions such as
cystic fibrosis, and
chronic bronchitis. ==Pathophysiology==