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Cough in Adults

by Noah Lechtzin, MD, MHS

Cough is an explosive expiratory maneuver that is reflexively or deliberately intended to clear the airways. It is one of the most common symptoms prompting physician visits.

Likely causes of cough (see Table: Some Causes of Cough) differ depending on whether the symptom is acute (present < 3 wk) or chronic.

In acute cough, the most common causes are

  • URI (including acute bronchitis)

  • Postnasal drip

  • COPD exacerbation

  • Pneumonia

In chronic cough, the most common causes are

  • Chronic bronchitis

  • Postnasal drip

  • Airway hyperresponsiveness after resolution of a viral or bacterial respiratory infection (ie, postinfection cough)

  • Gastroesophageal reflux

The causes in children (see Cough in Children) are similar to those in adults, but asthma and foreign body aspiration may be more common.

Very rarely, impacted cerumen or a foreign body in the external auditory canal triggers reflex cough through stimulation of the auricular branch of the vagus nerve. Psychogenic cough is even rarer and is a diagnosis of exclusion.

Patients with chronic cough may develop a secondary reflex or psychogenic component to their cough. Also, protracted coughing may injure the bronchial mucosa, which may trigger more coughing.

Some Causes of Cough

Cause

Suggestive Findings

Diagnostic Approach

Acute

URI (including acute bronchitis)

Rhinorrhea

Red, swollen nasal mucosa

Sore throat

Malaise

Clinical evaluation

Pneumonia (viral, bacterial, aspiration, rarely fungal)

Fever

Productive cough

Dyspnea

Pleuritic chest pain

Bronchial breath sounds or egophony

Chest x-ray

Cultures (eg, pleural fluid, blood, possibly bronchial washings) in seriously ill patients and patients with hospital-acquired pneumonia

Postnasal drip (allergic, viral, or bacterial origin)

Headache

Sore throat

Nausea

Cobblestoning of posterior oropharynx

Pale, boggy, swollen nasal mucosa

Clinical evaluation

Sometimes response to empiric antihistamine and decongestant therapy

CT of the sinuses if diagnosis is unclear

COPD exacerbation

Known diagnosis of COPD

Poor breath sounds

Wheezing

Dyspnea

Pursed lip breathing

Use of accessory muscles

Tripod positioning of the arms against the legs or examination table

Chest x-ray

Foreign body*

Sudden onset in a toddler who has no URI or constitutional symptoms

Chest x-ray (inspiratory and expiratory views)

Bronchoscopy

Pulmonary embolism*

Pleuritic chest pain

Dyspnea

Tachycardia

CT angiography

Less often, ventilation/perfusion scanning and possibly pulmonary arteriography

Heart failure*

Dyspnea

Fine crackles

Extrasystolic heart sound

Dependent peripheral edema

Chest x-ray

Brain (B-type) natriuretic peptide level

Chronic

Chronic bronchitis (in smokers)

Productive cough on most days of the month or for 3 mo of the year for 2 successive years in a patient with known COPD or smoking history

Frequent clearing of the throat

Dyspnea

Chest x-ray

Pulmonary function testing

Postnasal drip (allergic most likely)

Headache

Sore throat

Cobblestoning of posterior oropharynx

Pale, boggy, swollen nasal mucosa

Clinical evaluation

Sometimes response to empiric antihistamine and decongestant therapy

Allergy testing

Gastroesophageal reflux

Burning chest or abdominal pain that tends to worsen with consumption of certain foods, certain activities, or certain positions

Sour taste, particularly on awakening

Hoarseness

Chronic nocturnal or early morning cough

Clinical evaluation

Response to empiric H 2 blocker or proton pump inhibitor therapy

Sometimes 24-h esophageal pH probe if diagnosis is unclear

Asthma (cough variant)

Cough in response to various provoking factors (eg, allergens, cold, exercise)

Possibly wheezing and dyspnea

Pulmonary function testing

Methacholine challenge

Response to empiric bronchodilator therapy

Hyperresponsive airways after resolution of respiratory tract infection

Dry, nonproductive cough that may persist for weeks or months after an acute respiratory tract infection

Typically chest x-ray

ACE inhibitors

Dry, persistent cough that may occur within days or months after initiation of ACE inhibitor therapy

Response to stopping ACE inhibitor

Pertussis

Repeated bouts of 5 rapidly consecutive, forceful coughs during a single expiration, followed by a hurried and deep inspiration (whoop) or posttussive emesis

Cultures of nasopharyngeal specimens

Aspiration

Wet-sounding cough after eating or drinking

Chest x-ray

Sometimes modified barium pharyngography

Bronchoscopy

Tumor*

Atypical symptoms (eg, weight loss, fever, hemoptysis, night sweats)

Lymphadenopathy

Chest x-ray

If positive, chest CT and bronchoscopic biopsy

TB or fungal infections*

Atypical symptoms (eg, weight loss, fever, hemoptysis, night sweats)

Exposure history

Immunocompromise

Chest x-ray

Skin testing; if positive, sputum cultures and stains for acid-fast bacilli and fungi

Sometimes chest CT or bronchoalveolar lavage

*Indicates rare causes.

Evaluation

History

History of present illness should cover the duration and characteristics of the cough (eg, whether dry or productive of sputum or blood, and whether it is accompanied by dyspnea, chest pain, or both). Asking about precipitating factors (eg, cold air, strong odors) and the timing of the cough (eg, primarily at night) can be revealing.

Review of systems should seek symptoms of possible cause, including runny nose and sore throat (URI, postnasal drip); fever, chills, and pleuritic chest pain (pneumonia); night sweats and weight loss (tumor, TB); heartburn (gastroesophageal reflux); and difficulty swallowing or choking episodes while eating or drinking (aspiration).

Past medical history should note recent respiratory infections (ie, within previous 1 to 2 mo); history of allergies, asthma, COPD, and gastroesophageal reflux disease; risk factors for (or known) TB or HIV infection; and smoking history. Drug history should specifically include use of ACE inhibitors. Patients with chronic cough should be asked about exposure to potential respiratory irritants or allergens and travel to or residence in regions with endemic fungal illness.


Physical examination

Vital signs should be reviewed for the presence of tachypnea and fever.

General examination should look for signs of respiratory distress and chronic illness (eg, wasting, lethargy).

Examination of the nose and throat should focus on appearance of the nasal mucosa (eg, color, congestion) and presence of discharge (external or in posterior pharynx). Ears should be examined for triggers of reflex cough.

The cervical and supraclavicular areas should be inspected and palpated for lymphadenopathy.

A full lung examination is done, particularly including adequacy of air entry and exit; symmetry of breath sounds; and presence of crackles, wheezes, or both. Signs of consolidation (eg, egophony, dullness to percussion) should be sought.


Red flags

The following findings are of particular concern:

  • Dyspnea

  • Hemoptysis

  • Weight loss

  • Risk factors for TB or HIV infection


Interpretation of findings

Some findings point to particular diagnoses (see Table: Some Causes of Cough).

Other important findings are less specific. For example, the color (eg, yellow, green) and thickness of sputum do not help differentiate bacterial from other causes. Wheezing may occur with several causes. Hemoptysis in small amounts may occur with severe cough of many etiologies, although larger amounts of hemoptysis suggest bronchitis, bronchiectasis, TB, or primary lung cancer. Fever, night sweats, and weight loss may occur with many chronic infections as well as with cancer.


Testing

Patients with red flag findings of dyspnea or hemoptysis and patients in whom suspicion of pneumonia is high should have pulse oximetry and chest x-ray. Patients with weight loss or risk factors should have a chest x-ray and testing for TB and HIV infection.

For many patients without red flag findings, clinicians can base the diagnosis on history and physical examination findings and begin treatment without testing. For patients without a clear cause but no red flag findings, many clinicians empirically begin treatment for postnasal drip (eg, antihistamine and decongestant combinations, nasal corticosteroid sprays) or gastroesophageal reflux disease (eg, proton pump inhibitors, H 2 blockers). An adequate response to these interventions usually precludes the need for further evaluation.

Patients with chronic cough in whom presumptive treatment is ineffective should have a chest x-ray. If the x-ray findings are unremarkable, many clinicians sequentially test for asthma (pulmonary function tests with methacholine challenge), sinus disease (sinus CT), and gastroesophageal reflux disease (esophageal pH monitoring). Sputum culture is helpful for patients with a possible indolent infection, such as pertussis, TB, or nontuberculous mycobacterial infection. Sputum cytology is noninvasive and should be done if cancer is suspected and the patient is producing sputum or having hemoptysis. Chest CT and possibly bronchoscopy should be done in patients in whom lung cancer or another bronchial tumor is suspected (eg, patients with a long smoking history, nonspecific constitutional signs) and in patients in whom empiric therapy has failed and who have inconclusive findings on preliminary testing.


Treatment

Treatment is management of the cause.

There is little evidence to support the use of cough suppressants or mucolytic agents. Coughing is an important mechanism for clearing secretions from the airways and can assist in recovery from respiratory infections. Therefore, although patients often expect or request cough suppressants, such treatment should be given with caution and reserved for patients with a URI and for patients receiving therapy for the underlying disorder for whom cough is still troubling. Cough suppressants may help some patients with chronic cough who have a reflex or psychogenic component to their cough or who develop bronchial mucosal injury.

Antitussives depress the medullary cough center (dextromethorphan and codeine) or anesthetize stretch receptors of vagal afferent fibers in bronchi and alveoli (benzonatate). Dextromethorphan, a congener of the opioid levorphanol , is effective as a tablet or syrup at a dose of 15 to 30 mg po 1 to 4 times/day for adults or 0.25 mg/kg po qid for children. Codeine has antitussive, analgesic, and sedative effects, but dependence is a potential problem, and nausea, vomiting, constipation, and tolerance are common adverse effects. Usual doses are 10 to 20 mg po q 4 to 6 h as needed for adults and 0.25 to 0.5 mg/kg po qid for children. Other opioids (hydrocodone, hydromorphone, methadone, morphine) have antitussive properties but are avoided because of high potential for dependence and abuse. Benzonatate, a congener of tetracaine that is available in liquid-filled capsules, is effective at a dose of 100 to 200 mg po tid.

Expectorants are thought to decrease viscosity and facilitate expectoration (coughing up) of secretions but are of limited, if any, benefit in most circumstances. Guaifenesin (200 to 400 mg po q 4 h in syrup or tablet form) is most commonly used because it has no serious adverse effects, but multiple expectorants exist, including bromhexine, ipecac, and saturated solution of K iodide (SSKI). Aerosolized expectorants such as N -acetylcysteine and DNase are generally reserved for hospital-based treatment of cough in patients with bronchiectasis or cystic fibrosis. Ensuring adequate hydration may facilitate expectoration, as may inhalation of steam, although neither technique has been rigorously tested.

Topical treatments, such as acacia, licorice, glycerin, honey, and wild cherry cough drops or syrups (demulcents), are locally and perhaps emotionally soothing, but their use is not supported by scientific evidence.

Protussives, which stimulate cough, are indicated for such disorders as cystic fibrosis and bronchiectasis, in which a productive cough is thought to be important for airway clearance and preservation of pulmonary function. DNase or hypertonic saline is given in conjunction with chest physical therapy and postural drainage to promote cough and expectoration. This approach is beneficial in cystic fibrosis but not in most other causes of chronic cough.

Bronchodilators, such as albuterol and ipratropium or inhaled corticosteroids, can be effective for cough after URI and in cough-variant asthma.

Key Points

  • Danger signs include respiratory distress, chronic fever, weight loss, and hemoptysis.

  • Clinical diagnosis is usually adequate.

  • Occult gastroesophageal reflux disease should be remembered as a possible cause.

  • Antitussives and expectorants should be used selectively.

Resources In This Article

Drugs Mentioned In This Article

  • Drug Name
    Select Trade
  • DOLOPHINE
  • DILAUDID
  • ATROVENT
  • DELSYM
  • ACETADOTE
  • No US brand name
  • DURAMORPH PF, MS CONTIN
  • PROVENTIL-HFA, VENTOLIN-HFA
  • TESSALON

* This is a professional Version *