Cough -- a basic guide to diagnosing and treating cough illness Click on any of the headings or subheadings to rapidly navigate to the relevant section of the guidemap
Gastro-esophageal reflux disease
Angiotensin-Converting Enzyme Inhibitor-Induced Cough
Other causes of a cough to consider in children
Diagnostic approach to determining the cause of a chronic cough in adults
Commentary, criticism and controversy
This medical guidemap is a companion guidemap to the acute bronchitis guidemap, and it details a diagnostic and therapeutic approach to acute and chronic cough illnesses. It is chiefly based on the consensus guidelines published by a panel of medical experts headed by Richard Irwin, a reknown medical expert in the field of cough illness. The panel of experts included individuals with special expertise and research experience in the fields of adult and pediatric pulmonology, pharmacology and physiology. The Committee was international in scope, with individual panel members from the United States, Canada, Australia, and the United Kingdom. Representatives from the American College of Chest Physicians, the American Thoracic Society, the Canadian Thoracic Society, and the American College of Physicians were also active participants in the panel.
Those consensus guidelines are freely available online, and an adobe acrobat pdf file version of the guidelines can be accessed by clicking here. This medical guidemap is a simplified version of those guidelines, and intelligent laypeople may find it clinically useful. Although those consensus guidelines present a rational approach to the diagnosis and therapy of acute and chronic cough illness, the consensus guideline approach may not be the approach favored by your family doctor or consultant medical specialist. Nonetheless, the consensus guidelines do offer good general advice that should be very useful to an intelligent layperson, who wants to be actively involved in any medical decision-making process concerning his health care. I plan to only discuss the most common disease conditions causing acute or chronic cough illness -- interested readers can consult the official guidelines if they want more detailed information.
A cough is a protective mechanism that the human body has evolved to protect the airway from toxic inhalant gases, inhaled foreign bodies, or excessive upper or lower respiratory secretions. A persistent cough can be pathological and due to an acute or chronic cough illness.
The difference between an acute and chronic cough illness is based on the duration of the cough illness. A frequently used definition of acute cough illness is a cough illness that lasts less than 3 weeks. Any cough illness lasting longer than 3 weeks is labelled a chronic cough illness. However, some physicians label a cough illness lasting 3-8 weeks a subacute cough illness, and reserve the term chronic cough illness for a cough illness lasting longer than 8 weeks. There is no fixed time-point threshold, that if exceeded, mandates a diagnostic workup for a cough illness, but many physicians will institute a diagnostic workup for an unexplained cough illness lasting longer than 4-8 weeks.
There are many causes of a cough illness, but the vast majority are due to a limited number of medical conditions -- post-nasal drip syndromes, acute or chronic bronchitis, asthma, and gastroesophageal reflux disease. Multiple studies have shown that in approximately 95 percent of cases in immunocompetent patients, chronic cough illness results from a postnasal-drip syndrome related to conditions of the nose and sinuses, asthma, gastroesophageal reflux disease, chronic bronchitis due to cigarette smoking or other irritants, bronchiectasis, or the use of an angiotensin-converting-enzyme inhibitor drug. In the remaining 5 percent of cases, chronic cough illness is due to a variety of diseases, such as lung cancer, heart failure, and respiratory aspiration secondary to pharyngeal swallowing disorders. A chronic cough illness is usually due to a single cause 40-80% of the time. That means that there must be at least two conditions causing a chronic cough illness 20-60% of the time. Therefore, the diagnosis of a particular cause of a cough illness does not necessarily mean that other disease conditions are not also playing a causal role in the cough illness.
The following clinical conditions are the most likely conditions to cause a chronic cough illness (in rough order of likelihood).
The post-nasal drip syndrome is the most common cause of a chronic cough. There are many causes of a post-nasal drip, which is defined as the drip of nasal and/or sinus secretions down the back of the throat. The diagnosis of PNDS mainly depends on the patient describing certain sensations or symptoms in addition to a cough. Complaints include a sensation of something dripping down the back of the throat, a need to frequently clear the throat, a tickle in the throat, nasal congestion or a nasal discharge. A history of a preceding upper respiratory illness is often present. The patient may notice drainage in the back of his throat or a cobblestone appearance of the pharyngeal mucosa of the back of the throat. The nasal mucosa may be boggy and swollen in allergic rhinitis, while a purulent nasal discharge issuing from the area under the middle turbinate bone in the nose and/or face pain in the region of a sinus suggests a sinusitis.
A small percentage of patients may not have any PNDS symptoms, but because they respond to empiric treatment for PNDS, they are regarded as having "silent" PNDS.
The most common causes of PNDS include seasonal allergic rhinitis, perennial allergic rhinitis, perennial nonallergic rhinitis, postinfectious rhinitis, chronic (bacterial) sinusitis, nonallergic rhinitis due to medication abuse or environmental irritants, and nonallergic rhinitis associated with pregnancy.
The presence of seasonal rhinitis symptoms (sneezing, runny nose, congested nose) suggests a seasonal allergic rhinitis. Patients with allergic rhinitis often have a history of asthma or other allergies eg. contact dermatitis, and/or a family history of allergies. Allergy testing is most useful when there is a seasonal component to a PNDS-type cough illness, or if there is a strong association of the rhinitis symptoms with specific allergen exposures such as pollen or animal dander. Allergy testing for house dust mites or indoor mold may be warranted if perennial allergic rhinitis is more likely.
A history of a preceding upper respiratory tract infection ("common cold") suggests a post-infectious PNDS. Chronic sinus symptoms and/or a positive sinus X-ray suggests a chronic sinus PNDS. A history of inappropriate use of topical decongestant nasal sprays or nasal snorting of cocaine suggests the diagnosis of rhinitis medicamentosa. PNDS due to inhaled respiratory irritants is suggested by the enviromental history, which may include known occupational exposures to toxic volatile agents. Marked improvement of PNDS symptoms following removal of the offending exposure strongly suggests the diagnosis. The onset of PNDS during pregnancy, and its improvement following delivery, suggests pregnancy-related PNDS if no other PNDS-cause is apparent.
No definitive diagnostic criteria exist for PNDS-cough illness, and the diagnosis is usually suggested by the clinical features, the results of selective diagnostic tests and a positive response to anti-PNDS treatment. It is a diagnosis by inference.
Treatment of PNDS usually includes an antihistamine and a decongestant. Older generation antihistamines (which are sedating) work for non-allergic causes of PNDS-cough, such as perennial non-allergic rhinitis or post-infectious PNDS, because they also have prominent anticholineric activity [excessive sedation, increased problems with urination or increased intraocular pressures in glaucoma patients can occur with the use of an anticholinergic medication]. Newer generation antihistamines (which are non-sedating) do not have prominent anticholinergic activity, and they are primarily used for their specific antihistaminic activity. They are therefore specifically used in the treatment of allergic rhinitis (which is due to an allergen-induced release of histamine), and they are the preferred antihistamines because they are non-sedating and do not cause drowsiness. Oral decongestants (and/or a 5-day course of topical nasal decongestants) are often prescribed together with an antihistamine. Common decongestants include phenylephrine and pseudoephedrine [Insomnia, difficulty with urination (primarily in older men), jitteriness, fast heart rate or palpitations, worsening of hypertension, and increased intraocular pressures in patients with glaucoma are potential side-effects of the decongestant]. Allergic rhinitis is usually treated with non-sedating antihistamines and steroid nasal sprays. Persistent sinusitis, severe acute sinusitis and chronic sinusitis are usually treated with antibiotics, +/- decongestants and antihistamines. (See the Sinusitis guidemap for further details)
Asthma is the second most common cause of a chronic cough, second only to PNDS.
Asthma is a chronic inflammatory condition of the bronchial airways and it is characterised by cough, difficulty breathing (chest tightness) and wheezing, and a variable degree of airflow obstruction that can be identified by formal pulmonary function testing procedures. The presence of those airflow obstructive symptoms do not define asthma because many other clinical conditions can cause those same obstructive symptoms (eg, heart failure, chronic obstructive lung disease). The diagnosis of asthma requires the objective demonstration of airflow obstruction that is either spontaneously reversible or significantly reversible when the patient is actively treated with beta-agonist bronchodilators. The degree of reversibility varies, and the airflow obstruction must be at least 12% reversible to fit in with the diagnosis of asthma.
Asthmatic patients also demonstrate bronchial hyperresponsiveness, which is defined as the increased propensity of the bronchial airways to narrow in response to bronchoconstrictor agents. It consists of increased bronchial airway sensitivity, so that only a small concentration of a bronchoconstrictor agent is required to initiate a bronchoconstrictor response, and also a greater maximal response to the bronchoconstrictor agent (eg. histamine or methacholine). In a population of asthmatic patients, the severity of the airway hyperresponsiveness usually correlates with severity of the asthma and the amount of treatment needed to control the asthma symptoms. Bronchial hyperresponsiveness is also seen in other clinical conditions such as acute bronchitis, and in up to 30% of normal children. Therefore, its presence cannot be used to define asthma. However, the presence of bronchial hyperresponsiveness is a very sensitive test for asthma, and its absence makes the diagnosis of asthma unlikely.
The cough due to asthma responds to standard asthma therapy -- inhaled beta-agonist agents, inhaled or oral steroids and specific anti-inflammatory agents.
Cough-variant asthma
Cough-variant asthma is a term used to describe the presence of cough as the only symptom of asthma in a patient who has demonstrable bronchial hyperresponsiveness. Symptoms related to airflow obstruction -- wheezing and chest tightness -- are usually absent. The definitive diagnosis of cough-variant asthma is made when the cough goes away following empiric treatment of the suspected cough-variant asthma with bronchodilator agents. It is implausible that cough-variant asthma is the cause of a chronic cough if bronchial hyperresponsiveness cannot be demonstrated by formal testing. However, it is not possible to perform formal testing of bronchial hyperresponsivenss in very young children, and the diagnosis of cough-variant asthma is suggested when the child has a typical history of a cough that is triggered by a viral respiratory illness or allergen exposure, a cough which is worse at night, and a cough which is exacerbated by exercise, cold air or smoke inhalation; coupled with a favorable treatment response to standard asthma medications (beta-agonists, asthma anti-inflammatory agents, or steroids). The greatest long-term therapeutic benefit is likely to be obtained from steroid therapy, administered either orally or by inhalation. The inhaled medications should be administered from a dry powder device, or a pressurized metered-dose inhaler together with a spacer or aerochamber. Inhalation from a pressurized metered-dose inhaler alone can exacerbate the cough. The maximum therapeutic benefit from steroids is usually seen in 6-8 weeks.
Gastro-esophageal reflux disease (GERD).
GERD-induced cough is the third most common cause of a chronic cough, after PNDS and asthma.
Acid reflux from the stomach into the lower esophagus is a common event and it is often asymptomatic. Excessive reflux may produce symptoms of heartburn, which is a burning discomfort in the central chest in the region of the sternum or below the sternum (epigastrium). Prolonged exposure of the esophagus to acid reflux can lead to inflammation of the esophagus, esophageal ulcers, and secondary complications like bleeding and stricture formation due to scarring. However, significant acid reflux can be present without GERD symptoms or evidence of esophageal inflammation. In up to 40% of patients with GERD, a chronic cough may be the sole manifestation of the condition.
The amount of reflux can vary. Large volume reflux is rare, and it can result in reflux of stomach fluid into the upper esophagus and subsequently into the lungs. Pulmonary aspiration may cause a secondary aspiration pneumonia, and the patient may present with a fever, purulent and/or bloody sputum, wheezing, shortness of breath, cough and chest pain. Microaspiration secondary to small amounts of acid reflux results in less serious respiratory complications, and cough and hoarseness (due to laryngeal inflammation) may be prominent symptoms. GERD can produce a chronic cough even without microaspiration of acid reflux into the lungs. The chronic cough is thought to be induced by nerve impulses mediated via the vagus nerve, and it occurs when acid refluxes into the lower esophagus and stimulates the vagal nerve endings in that area. A cough-reflux self-perpetuating cycle may exist, whereby cough from any cause precipitates further gastroesophageal reflux.
Cough due to GERD is often suspected when a chronic cough patient has no evidence of PNDS or asthma, but has heartburn symptoms +/- a sour taste in the mouth due to waterbrash (reflux of acid material into the throat). 10-20% of adults with GERD symptoms have an associated cough that is thought to be secondary to vagus nerve stimulation. GERD with heartburn symptoms is thought to account for about 5-10% of chronic cough illness in adults. The diagnosis of GERD-induced cough is made on the basis of the accompanying reflux symptoms, and the disappearance of the cough with effective anti-reflux therapy. In children, GERD may cause 15% of chronic cough illnesses, and it is the third most frequent cause of a chronic cough, following only asthma and sinusitis in frequency. Children present in a similar fashion to adults, although GERD symptoms are often more prominent.
The diagnosis of GERD as a cause of a chronic cough can only be made with certainty when the cough goes away with specific anti-reflux therapy. It often takes months for the cough symptom to resolve. A 24-hour ambulatory esophageal pH monitoring test can be performed to verify that acid is refluxing into the lower esophagus, and it also allows the treating physician to demonstrate that there is a temporal relationship between the cough symptom and acid reflux. Esophagoscopy (looking into the lower esophagus with an endoscopic device) can demonstrate the presence of esophageal inflammation, but significant reflux can be present in the absence of demonstrable esophageal inflammation. Because GERD (without heartburn symptoms) may also be responsible for a cough in chronic cough patients who have a cough due to another cause (eg. PNDS), a 24-hour ambulatory pH monitoring test may be warranted if chronic cough patients do not respond well to specific therapy targeted at the primary cause of the chronic cough (eg. anti-PNDS therapy). Empiric therapeutic trials are a common approach to the diagnosis of a chronic cough. Therefore, the treating physician may decide to institute empiric anti-reflux therapy, without performing a 24-hour ambulatory esophageal pH monitoring test, if a diagnostic protocol in a chronic cough patient is negative for PNDS or asthma and the chest X-ray is normal -- even if there are no active reflux symptoms. However, if empiric anti-reflux treatment fails, full investigation of GERD may be necessary, because the anti-reflux therapy may not have been intense enough or the GERD may be resistant to intensive antireflux therapy.
The main objective of GERD therapy is to decrease the frequency and duration of reflux events, and to decrease the irritative nature of gastric secretions. Conservative measures should be tried in all patients:- weight reduction, a high-protein, low-fat antireflux diet that eliminates foods and beverages with a low pH, elevation of the head of the bed, and lifestyle measures such as avoiding coffee and smoking. Those measures, in addition to prokinetic agents (eg. cisapride or domperidone) and/or H2 antagonists (eg. cimetidine or ranitidine), result in the resolution of cough in 70 to 100% of adult patients, although the mean time to recovery may be very long at about 4-6 months. Proton pump inhibitors (eg. omeprazole or lansoprazole) have also been used with anecdotal success. However, no clinical trials utilizing those agents for GERD-induced cough have been published. Antireflux surgery is generally reserved for patients with proven GERD who have failed to respond to 3-6 months of maximal medical therapy.
Chronic bronchitis (CB) accounts for approximately 5% of patients who seek attention for chronic cough illness. Most CB patients do not initially seek medical attention for their cough, because they presume that they just have a "smoker's cough".
Chronic bronchitis is characterized by a recurrent productive cough on most days over a period of at least 3 months, and for more than two consecutive years, in a patient in whom other causes of a chronic cough have been excluded. It is a component of the disease entity called chronic obstructive pulmonary disease (COPD), which can be readily diagnosed by a clinician, and subsequently confirmed by pulmonary function testing.
CB is unlikely to occur in nonsmokers without significant long-term exposure to dusts or fumes. Cigarette smoking is the most common cause of CB. Smoke can induce chronic airway inflammation and mucus hypersecretion, and it impairs mucociliary clearance of sputum. Large volumes of bronchial secreations are produced and the voluminous sputum needs to be constantly cleared from the bronchial airways by expectoration. The sputum is usually clear or whitish in appearance. The CB patient may also have evidence of airway obstruction, and complain of wheezing and breathing difficulty.
The cough due to CB has been shown to disappear or markedly diminish in 90-100% of CB patients following the cessation of smoking.
The most frequent complication of CB is respiratory infection, which will lead to an increase in sputum production and cough. Although most lower respiratory infections are viral in origin, bacterial superinfection is common in CB. Antibiotic therapy is frequently prescribed if a CB patient develops evidence of a superimposed acute bronchitis flare-up -- the patient may present with fever, increased wheezing and difficulty breathing, or increased sputum purulence. See the Acute Bronchitis guidemap for more information. Because long-term smoking also predisposes a CB patient to the development of bronchogenic cancer, a CB patient should seek medical attention if the pattern of his productive cough illness changes, or if his sputum becomes blood-tinged.
Many respiratory agents are used to treat CB, and all CB patients should seek medical attention, so that a long-term treatment plan can be instituted.
Bronchiectasis is defined by an abnormal destructive pathology of the bronchial airways, and is caused by the interaction of a respiratory insult (toxic inhalational agent, severe childhood respiratory infections, recurrent aspiration) and a disorder of host defences (eg. cystic fibrosis). The resulting inflammatory response in the bronchi sets up a vicious cycle of progressive airway damage, beginning with impairment of bronchial clearance that eventually leads to chronic colonization of the airways by bacterial organisms. The persistent low-grade bacterial infection causes further airway damage, and the cycle continues, leading to severe destruction of the walls of the bronchial airways. Cystic fibrosis is the most common cause of childhood bronchiectasis in North America. Bronchiectasis in children can also follow severe pneumonia, a retained bronchial foreign body, hydrocarbon aspiration, and congenital disorders of the bronchial ciliary system.
The cardinal symptom is chronic cough with production of sputum. Most patients will produce sputum on a chronic basis, sometimes in copious amounts. The sputum is usually mucoid or mucopurulent, becoming frankly purulent during an exacerbation. At all times it is thick, tenacious, and difficult to expectorate. Wheezing is frequently present, and many patients have bronchial hyperresponsiveness, which can be demonstrated by a positive methacholine challenge test. Some patients, particularly those with cystic fibrosis, have chronic constitutional symptoms (tiredness, poor appetite, weight loss).
Bronchiectasis is diagnosed by a compatible clinical history, chest X-ray, and/or a CT scan of the chest. Treatment is best organized by a pulmonologist, and includes chest physiotherapy, drugs to stimulate mucociliary clearance, and systemic and/or aerolized antibiotics.
This describes the cough that persists after a common cold or episode of acute bronchitis. Most attacks of acute bronchitis resolve in less than 3 weeks, but 10-25% of patients have a persistent cough lasting >3 weeks. The cough is thought to be due to persistent airway inflammation and bronchial hyperresponsiveness. The persistent cough usually resolves spontaneously with the passage of time. Children may have 6-8 respiratory infections per year, and back-to-back respiratory infections may occur during the winter months, resulting in a persistent post-infectious cough.
Most of these post-infectious cough illnesses follow a viral infection, but a small percentage of those respiratory infections are due to bacterial organisms eg. Mycoplasma, chlamydia, Bordetella pertussis (whooping cough). See the Acute Bronchitis guidemap for more information about those bacterial organisms.
The diagnosis is one of exclusion. No other causes of a persistent cough following a recent respiratory infection should be present (eg. PNDS or asthma) and the chest X-ray should be normal. Although the cough usually resolves spontaneously, some physicians prescribe oral or inhalational steroids, which have been shown to sometimes be useful in attenuating the cough.
Bronchogenic cancer refers to a cancer that originates in the bronchial airways of the lung. Tobacco smoking is the cause of 85% of lung cancers. The risk of developing bronchogenic cancer increases with the duration of smoking and the quantity of tobacco smoked per day. Other causal factors include asbestos, uranium, and radon gas.
Bronchogenic cancer accounts for <2% of chronic cough illnesses in older adults. The cough is thought to be due to stimulation of the cough receptors in the bronchi. A cough is more likely to be present when the lung cancer is in the larger, more central bronchial airways. The cough may be productive of sputum, which may also be blood-stained.
Bronchogenic cancer should be excluded in all smokers who have a persistent cough or blood-stained sputum, and in all chronic bronchitis patients who have a change in their cough pattern. The diagnosis is usually made by chest X-ray, or chest CT scan, or sputum cytology. A definitive diagnosis usually requires biopsy of the cancerous lesion via a flexible bronchoscope (flexible endoscopic instrument that is passed into the bronchial airways). Lung cancer is very unlikely if a non-smoker has a normal chest x-ray, and other causes of a chronic cough should preferentially be pursued. If a smoker (over the age of 40 years) has a normal chest x-ray, flexible bronchoscopy is recommended if the cough persists for >4 weeks after the cessation of smoking.
Treatment of bronchogenic cancer is primarily surgical. Radiotherapy and chemotherapy may also be used.
Angiotensin-Converting Enzyme Inhibitor-Induced Cough
ACEIs are drugs used to treat heart failure and hypertension, and a chronic non-productive cough is a frequent side-effect of the drug. All drugs in this class can produce a persistent cough, and the likelihood is not related to the dose of the drug. The cough may appear hours-days-months after ACEI drug treatment is instituted. Approximately 10% of ACEI-treated patients develop a cough, which disappears in 3-4 weeks if the drug is discontinued.
Because no laboratory test will predict who has an ACEI-induced cough, the diagnosis should be considered in any patient who has a cough while taking an ACEI. Treatment involves discontinuing the drug. The diagnosis is confirmed if the cough disappears, or substantially improves, within 4 weeks after discontinuing the drug.
Other causes of a cough to consider in children
Asthma, upper and lower respiratory tract infections, and GERD are the most common causes of acute and chronic cough in children.
Rare causes of a chronic cough illness include congenital anomalies of intra-thoracic structures (eg. congenital anomalies of the aortic arch and pulmonary artery that compress the trachea or major bronchi); congenital heart diseases, and aspirated foreign bodies that enter the bronchial airways. A foreign body should always be suspected in young children between the ages of 1-3 years who have an unexplained cough. While most children present within 24 hours of the event, 20% of children present more than 1 week after inhaling the foreign body. Food or food material accounts for 80% of the aspirated material, and peanuts are responsible for 50% of all aspirations.
Enviromental factors that may cause a persistent cough in children include inhalational exposure to passive second-hand smoke, wood-burning stoves, or kerosene heaters.
Diagnostic approach to determining the cause of a chronic cough in adults
There is no "best" diagnostic approach, and different physicians may work-up a chronic cough in a different manner. The diagnosis of a chronic cough illness may be made in >70% of cases on the basis of the history alone. Often, the history provides a series of important clues, which collectively suggest that a particular cause is likely (eg. PNDS), and diagnostic testing should be primarily targeted at the likely cause (eg. sinus X-rays to look for evidence of sinusitis-induced PNDS).
One diagnostic approach that a physician may adopt -- if the cause of the cough is not immediately apparent after taking the history and examining the patient, and there is no history of chronic exposure to enviromental respiratory irritants -- is to first consider the possibility of an ACEI-induced cough and/or chronic bronchitis if the patient is a smoker. If a chronic cough disappears within 4 weeks after discontinuing an ACEI drug, then an ACEI-induced cough is likely. If a chronic cough disappears within 4 weeks of smoking cessation, then chronic bronchitis is likely.
If those causes are unlikely (or have been excluded), then a chest X-ray would be performed. Some physicians always initiate the diagnostic workup of a chronic cough illness by first ordering a chest x-ray, as a screening test, in all patients with a chronic cough. If the chest X-ray is normal, then the most likely causes are PNDS, asthma and GERD. Those diagnoses would likely be pursued first (in that order). If the chest X-ray is abnormal, further diagnostic workup will depend on the pattern of the X-ray findings. A mass lesion may suggest bronchogenic cancer, and further diagnostic workup may include sputum cytology, a chest CT scan, and flexible bronchoscopy. If the chest X-ray suggests the likelihood of heart failure, further diagnostic studies may include echocardiography, and other cardiac studies. If the chest X-ray suggests that bronchiectasis is likely, flexible bronchoscopy and sputum culture would be indicated. If the chest X-ray suggests that an aspiration pneumonia is present, the physician may consider diagnostic studies to look for an occult foreign body in the bronchial airways or diagnostic studies to assess the neuromuscular function of the pharyngeal swallowing mechanism if the patient often chokes when eating .
The treatment of cough can be (1) therapy that controls, prevents, or eliminates the cough (ie, antitussive therapy), or (2) therapy that makes the cough more effective (ie, protussive therapy).
Antitussive Therapy
Antitussive therapy can be either specific or nonspecific. It is indicated when a cough performs no useful function, such as clearing the airways in a patient with chronic bronchitis or bronchiectasis. Specific antitussive therapy is directed at the the specific cause of the cough (eg. smoking cessation in chronic bronchitis) or presumed operant pathophysiologic mechanism responsible for the cough (eg. antihistamines and decongestants for PNDS in allergic rhinitis, or anti-reflux medications for GERD-induced cough). Nonspecific antitussive therapy is directed at the symptom rather than the underlying cause or pathophysiology, and aims to control rather than eliminate the cough. It is indicated when definitive, specific therapy cannot be given either because the cause of cough is unknown, or because definitive therapy has not had a chance to work or will not work (eg. inoperable lung cancer). Specific antitussive therapy is successful in 70-98% of cases. Nonspecific antitussive therapy has a limited role to play in the management of a cough, because there is a high probability that the cause of cough can be determined and that specific treatment will be successful. Examples of non-specific antitussive agents include drugs such as codeine and dextromethorphan.
Protussive therapy
Protussive therapy is indicated when the cough performs a useful function and needs to be encouraged (eg. to clear sputum from the airways in patients with chronic bronchitis, bronchiectasis, or pneumonia). Protussive therapy is treatment that increases cough effectiveness with or without increasing cough frequency. The protussive drug that is most frequently used in community practice is guaifenesin, which is a mucolytic agent that is reputed to decrease the viscosity of mucus.
Commentary, criticism and controversy
Insightful questions and comments from readers will be included in this section.
Disclaimer: My medical guidemaps reflect my personal approach to clinical problems, and although my personal approach is primarily based on a thorough evaluation of the evidence-based medical literature, my personal approach should not be regarded as the "standard of care". My medical guidemaps should only be used if the reader-user has substantial reason to believe that the clinical advice contained in the guidemaps is valid and accurate. My medical guidemaps do not represent a personal medical service and they should not be used as a substitute for consulting a physician or other health-care provider. My medical guidemaps should be perceived as being an altruistic educational resource that is only applicable to medical practice in the USA and certain other countries.