Coughing is one of the most common symptoms for which outpatient care is sought, responsible for approximately 30 million clinician visits annually in the United States.
Types of cough
Acute cough exists for less than three weeks and is most commonly due to an acute respiratory tract infection.
Subacute cough has been present for three to eight weeks.
Chronic cough persists for more than eight weeks
Why do I cough?
Cough is a protective mechanism to protect the airways from harmful irritants. Cough receptors are located in different parts of the respiratory system, diaphragm and even in certain areas of the gastrointestinal system. When they are exposed to irritating substances, they are stimulated.
The most common causes of chronic cough are upper airway cough syndrome (due to postnasal drip), asthma, and gastroesophageal reflux. A cough can often linger long after the other acute symptoms of an infection have dissipated. In nearly half of patients, subacute cough was post-infectious and resolved without specific therapy. Cough may also be a complication of drug therapy, particularly with ACE inhibitors.
Upper airway cough syndrome
Often related to postnasal drip. Symptoms of postnasal drip include frequent nasal discharge, a feeling of liquid dripping into the back of the throat, and frequent throat clearing. Underlying reasons can be: irritation of the mucous membrane inside the nose caused by allergies, colds, and inflammation of the sinuses (sinusitis).
The second leading cause of persistent cough in adults, and the most common cause in children. Cough due to asthma is commonly accompanied by episodic wheezing and difficult or labored breathing. Asthma related cough can be seasonal, may follow an upper respiratory tract infection, or may worsen upon exposure to cold, dry air, dust, mold, or to certain fumes or fragrances.
Gastroesophageal reflux (GERD)and laryngopharyngeal reflux (LPR)
GERD is the second or third most common cause of persistent cough. It can be a chronic symptom of mucosal damage caused by stomach acid coming up from the stomach into the esophagus. It is sometimes associated with heartburn, but not always. GERD mainly occurs when the patient is lying down.
LPR is caused by stomach acid rising into the larynx, the voice box, and occurs mostly when the patient is upright or during physical exertion; symptoms include hoarseness, difficulty swallowing, and non-productive throat clearing.
A non-productive cough is a well-recognized complication of treatment with angiotensin converting enzyme (ACE) inhibitors used for the treatment of high blood pressure. It usually begins within one week of starting on the medication, but the onset can be delayed up to six months. It often presents with a tickling, scratchy, or itchy sensation in the throat.
Defined as the presence of cough and sputum production on most days over at least a three-month period for over two consecutive years in a patient without other explanations for the cough. Almost all patients are smokers, except a small number who have chronic exposure to other fumes or dusts or chronic infections leading to a condition called bronchiectasis, in which the damage leaves the airways widened and scarred. Chronic bronchitis is one of the most frequent causes of chronic cough.
Although lung cancer is a feared diagnosis, it is the cause of less than 2% of chronic cough cases. It may be suspected in patients with a new cough or a recent change in chronic “smoker’s cough,” a cough that persists for more than one month after stopping smoking, or coughing up blood.