Age, occupational history, environmental exposures, risk of coronavirus disease 2019 (COVID-19) (see Chapter 32), and duration of cough.
Use of tobacco, cannabis, e-cigarettes (vaping).
Dyspnea (at rest or with exertion).
Vital signs (heart rate, respiratory rate, body temperature); pulse oximetry.
Chest radiography, especially when unexplained cough lasts longer than 3–6 weeks.
Cough is the most common symptom for which patients seek medical attention. This symptom leads to nearly 30 million clinician office visits and costs billions of dollars annually in the United States. Cough adversely affects personal and work-related interactions, disrupts sleep, and often causes discomfort of the throat and chest wall. Most people seeking medical attention for acute cough desire symptom relief; few are worried about serious illness. Cough results from stimulation of mechanical or chemical afferent nerve receptors in the bronchial tree. Effective cough depends on an intact afferent–efferent reflex arc, adequate expiratory and chest wall muscle strength, and normal mucociliary production and clearance. Although typically just a transient, bothersome symptom, cough can induce pathology including cough headache, cough syncope, cervical artery dissection, splenic rupture, and syncope. For many, cough causes anxiety and insomnia, impacting quality of life. Asthmatic patients with chronic cough have worse respiratory symptoms, reduced lung function, and greater health care utilization.
Distinguishing acute (less than 3 weeks), persistent (3–8 weeks), and chronic (more than 8 weeks) cough illness syndromes is a useful first step in evaluation. Postinfectious cough lasting 3–8 weeks has also been referred to as subacute cough to distinguish this common, distinct clinical entity from acute and chronic cough.
In healthy adults, most acute cough syndromes are due to viral respiratory tract infections. Additional features of infection such as fever, nasal congestion, and sore throat help confirm this diagnosis. Dyspnea (at rest or with exertion) may reflect a more serious condition, and further evaluation should include assessment of oxygenation (pulse oximetry or arterial blood gas measurement), airflow (peak flow or spirometry), and pulmonary parenchymal disease (chest radiography). The timing and character of the cough are not very useful in establishing the cause of acute cough syndromes, although cough-variant asthma should be considered in adults with prominent nocturnal cough, and persistent cough with phlegm increases the likelihood of chronic obstructive pulmonary disease (COPD). The presence of posttussive emesis or inspiratory whoop in adults modestly increases the likelihood of pertussis, and the absence of paroxysmal cough and the presence of fever decrease its likelihood. Uncommon causes of acute cough should be suspected in those with heart disease (heart failure [HF]) or hay fever (allergic rhinitis) and those with occupational risk factors (such as farmworkers).
2. Persistent and chronic cough
Cough due to acute respiratory tract infection resolves within 3 weeks in ...