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For further information, see CMDT Part 2-02: Cough

Key Features

Essentials of Diagnosis

  • Inquire about

    • Age

    • Tobacco use, e-cigarette use, vaping, cannabis use

    • Occupational history

    • Environmental exposures

    • Risk for SARS-CoV-2 infection

    • Duration of cough; dyspnea (at rest or with exertion)

    • Vital signs (heart rate, respiratory rate, body temperature); pulse oximetry; chest examination

    • Chest radiography, especially when unexplained cough lasts more than 3–6 weeks

General Considerations

  • Cough results from stimulation of mechanical or chemical afferent nerve receptors in the bronchial tree

  • Cough illness syndromes are defined as acute (< 3 weeks), persistent (3–8 weeks), or chronic (> 8 weeks)

  • Postinfectious cough lasting 3–8 weeks also called subacute cough to distinguish this distinct clinical entity from acute and chronic cough

  • The prevalence of pertussis infection in adults with a cough lasting > 3 weeks is 20%, although exact prevalence is difficult to ascertain due to the limited sensitivity of diagnostic tests

Clinical Findings

Symptoms and Signs

  • Timing and character of cough are not very useful in establishing cause

  • However, cough-variant asthma should be considered in adults with prominent nocturnal cough, and persistent cough with phlegm increases the patient's likelihood of chronic obstructive pulmonary disease (COPD)

  • Search for additional features of infection such as fever, nasal congestion, and sore throat

  • Dyspnea (at rest or with exertion) may reflect a more serious condition

  • Signs of pneumonia

    • Tachycardia

    • Tachypnea

    • Fever

    • Rales

    • Decreased breath sounds

    • Fremitus

    • Egophony

  • Signs of acute bronchitis: wheezing and rhonchi

  • Signs of chronic sinusitis: postnasal drip

  • Signs of COPD

    • Abnormal match test (inability to blow out a match from 10 inches away)

    • Maximum laryngeal height < 4 cm (measured from the sternal notch to the cricoid cartilage at end expiration)

  • Signs of heart failure (HF)

    • Symmetric basilar rales

    • Abnormal jugular venous pressure

    • Positive hepatojugular reflux

Acute cough

  • Most due to viral respiratory tract infections

  • Presence of post-tussive emesis or inspiratory whoop in adults modestly increases the likelihood of pertussis, and absence of paroxysmal cough and the presence of fever decreases its likelihood

  • Less common causes include

    • HF

    • Hay fever (allergic rhinitis)

    • Occupational factors

Persistent cough

  • Usually due to

    • Angiotensin-converting enzyme (ACE) inhibitor therapy

    • Postnasal drip

    • Asthma

    • Gastroesophageal reflux disease (GERD)

  • Less common causes

    • Bronchogenic carcinoma

    • Chronic bronchitis

    • Bronchiectasis

    • Other chronic lung disease

    • HF

Chronic cough

  • May suggest Sjögren syndrome if accompanied by dry eyes

  • If dry, may be first symptom of idiopathic pulmonary fibrosis

  • If productive (especially with hemoptysis), consider tuberculosis

Differential Diagnosis

Acute cough

  • Viral upper respiratory infection or postviral cough (most common)

  • Infection with SARS-CoV-2

  • Asthma

  • Allergic rhinitis

  • HF

  • ACE inhibitor therapy

Persistent and ...

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