Acute bronchitis is inflammation of the tracheobronchial tree, commonly following an upper respiratory infection in the absence of chronic lung disorders. The cause is almost always a viral infection. The pathogen is rarely identified. The most common symptom is cough, with or without fever, and possibly sputum production. Diagnosis is based on clinical findings. Treatment is supportive; antibiotics are usually unnecessary. Prognosis is excellent.
(See also Cough in Children.)
Acute bronchitis is frequently a component of an upper respiratory infection (URI) caused by rhinovirus, parainfluenza, influenza A or B virus, respiratory syncytial virus, coronavirus, or human metapneumovirus (1). Bacteria, such as Mycoplasma pneumoniae, Bordetella pertussis, and Chlamydia pneumoniae, cause less than 5% of cases; these sometimes occur in outbreaks. B. pertussis infections in adults presenting as acute bronchitis have been recognized as a manifestation of waning immunity from childhood vaccination (2). Acute bronchitis is part of the spectrum of illness that can occur with SARS-CoV-2 infection, and testing for this virus is appropriate. Systemic symptoms such as fever, myalgias as well as sore throat, gastrointestinal symptoms, and loss of smell and taste are more common with the SARS-CoV-2 virus than others.
Acute inflammation of the tracheobronchial tree in patients with underlying chronic bronchial disorders (eg, asthma, chronic obstructive pulmonary disease [COPD], bronchiectasis, cystic fibrosis) is considered an acute exacerbation of that disorder rather than acute bronchitis. In these patients, the etiology, treatment, and outcome differ from those of acute bronchitis. As exacerbations often precede the diagnosis of an underlying chronic bronchial disorder, clinical evaluation of a patient with acute bronchitis should include assessment for the presence of chronic respiratory symptoms (eg, dyspnea, chronic cough with or without sputum, wheezing) preceding the acute illness.
Pearls & Pitfalls
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General references
1. Miller JM, Binnicker MJ, Campbell S, et al. A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology. Clin Infect Dis 2018;67(6):e1-e94. doi:10.1093/cid/ciy381
2. Mattoo S, Cherry JD. Molecular pathogenesis, epidemiology, and clinical manifestations of respiratory infections due to Bordetella pertussis and other Bordetella subspecies. Clin Microbiol Rev 2005;18(2):326-382. doi:10.1128/CMR.18.2.326-382.2005
Symptoms and Signs of Acute Bronchitis
Symptoms are a nonproductive or mildly productive cough accompanied or preceded by URI symptoms. Typical symptom duration before presentation is usually 5 days or more (1). Subjective dyspnea results from chest pain caused by musculoskeletal discomfort due to coughing or chest tightness related to bronchospasm, not from hypoxia.
Signs are often absent but may include scattered rhonchi and wheezing. Sputum may be clear or purulent. Sputum characteristics do not correspond with a particular etiology (ie, viral vs bacterial) or response to antibiotic therapy. Mild fever may be present, but high or prolonged fever is unusual and suggests influenza, pneumonia, or COVID-19.
On resolution, cough is the last symptom to subside and often takes 2 to 3 weeks but rarely can take even longer to do so.
Symptoms and signs reference
1. Ebell MH, Merenstein DJ, Barrett B, et al. Acute cough in outpatients: what causes it, how long does it last, and how severe is it for different viruses and bacteria? [published correction appears in Clin Microbiol Infect 2025 Jan;31(1):142. doi: 10.1016/j.cmi.2024.09.013.]. Clin Microbiol Infect 2024;30(12):1569-1575. doi:10.1016/j.cmi.2024.06.031
Diagnosis of Acute Bronchitis
Clinical evaluation
Sometimes chest radiographs to exclude other disorders
Diagnosis is primarily based on clinical presentation.
Patients who complain of dyspnea should have pulse oximetry to exclude hypoxemia.
Chest radiographs are done if clinical findings (eg, ill appearance, mental status change, high fever, tachypnea, hypoxemia, abnormal auscultatory findings such as altered breath sounds or crackles) suggest pneumonia or other serious illness. Older patients are the occasional exception in whom a lower threshold for radiography is required, because they may have pneumonia without fever and auscultatory findings, presenting instead with altered mental status and tachypnea.
Microbiologic testing (eg, sputum Gram stain and culture) is usually unnecessary. However, patients with signs or symptoms suggestive of COVID-19 should be tested for SARS-CoV-2. Diagnostic testing for influenza and pertussis in nasopharyngeal swab specimens should also be considered if there is high clinical suspicion based on exposure and/or clinical features. Patients with 10 to 14 days of ongoing symptoms should be evaluated for pertussis, particularly if they are unvaccinated, have a persistent paroxysmal cough or intermittent characteristic whoop and/or retching, or exposure to a confirmed case. Testing for Mycoplasma and Chlamydia infection is not necessary unless part of an outbreak. Viral panel testing is not usually recommended because results do not affect treatment.
Cough resolves within 2 weeks in 80% of patients; in the other 20%, it may take up to 8 weeks to resolve (1). Patients with cough that worsens after initial improvement and those with cough that lingers for > 8 weeks should undergo further evaluation, including a chest x-radiograph. Evaluation for noninfectious causes of chronic cough, such as asthma (including cough-variant asthma), postnasal drip, and gastroesophageal reflux disease, can usually be made on the basis of the clinical presentation. Differentiation of cough-variant asthma may require pulmonary function testing.
Diagnosis reference
1. Hounkpatin H, Stuart B, Zhu S, et al. Post-consultation acute respiratory tract infection recovery: a latent class-informed analysis of individual patient data. Br J Gen Pract 2023;73(728):e196-e203. doi:10.3399/BJGP.2022.0229
Treatment of Acute Bronchitis
Symptom relief (eg, acetaminophen, hydration, possibly antitussives)Symptom relief (eg, acetaminophen, hydration, possibly antitussives)
Inhaled beta-agonist for wheezing
Nearly all patients require only symptomatic treatment, such as acetaminophen and hydration. Evidence supporting efficacy of Nearly all patients require only symptomatic treatment, such as acetaminophen and hydration. Evidence supporting efficacy ofroutine use of other symptomatic treatments, such as antitussives, mucolytics, and bronchodilators, is weak. Ibuprofen is generally not recommended as it has not been found to be helpful in aiding symptom resolution (use of other symptomatic treatments, such as antitussives, mucolytics, and bronchodilators, is weak. Ibuprofen is generally not recommended as it has not been found to be helpful in aiding symptom resolution (1). Antitussives (dextromethorphan) with or without mucolytics (guaifenesin) should be considered only if the cough is distressing or interfering with sleep. Patients with wheezing may benefit from an inhaled beta2-agonist (eg, albuterol) for a few days. Broader use of beta2-agonists is not recommended because adverse effects such as tremor, nervousness, and shaking are common ((dextromethorphan) with or without mucolytics (guaifenesin) should be considered only if the cough is distressing or interfering with sleep. Patients with wheezing may benefit from an inhaled beta2-agonist (eg, albuterol) for a few days. Broader use of beta2-agonists is not recommended because adverse effects such as tremor, nervousness, and shaking are common (2).
Acute bronchitis in otherwise healthy patients is a major cause of antibiotic overuse. The low incidence of bacterial causation, self-limiting nature of acute bronchitis, and the risk of adverse effects argue against widespread antibiotic use (3). Limiting inappropriate antibiotic use, which may be as high as 45% worldwide, is key in preventing antibiotic resistance (4). Patient education and delayed prescription (ie, to be only filled if no improvement after at least a couple of days) help limit unnecessary antibiotic use. Oral antibiotics are typically not used except in patients with pertussis or during known outbreaks of bacterial infection (mycoplasma, chlamydia). A macrolide such as azithromycin or clarithromycin is the preferred choice.or during known outbreaks of bacterial infection (mycoplasma, chlamydia). A macrolide such as azithromycin or clarithromycin is the preferred choice.
Pearls & Pitfalls
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Treatment references
1. Kinkade S, Long NA. Acute Bronchitis. Am Fam Physician 2016;94(7):560-565.
2. Becker LA, Hom J, Villasis-Keever M, van der Wouden JC. Beta2-agonists for acute cough or a clinical diagnosis of acute bronchitis. Cochrane Database Syst Rev 2015;2015(9):CD001726. Published 2015 Sep 3. doi:10.1002/14651858.CD001726.pub5
3. Llor C, Moragas A, Bayona C, et al. Efficacy of anti-inflammatory or antibiotic treatment in patients with non-complicated acute bronchitis and discoloured sputum: randomised placebo controlled trial. BMJ 2013;347:f5762. doi:10.1136/bmj.f5762
4. Kasse GE, Cosh SM, Humphries J, Islam MS. Antimicrobial prescription pattern and appropriateness for respiratory tract infection in outpatients: a systematic review and meta-analysis. Syst Rev 2024;13(1):229. Published 2024 Sep 6. doi:10.1186/s13643-024-02649-3
Key Points
Acute bronchitis is viral in > 95% of cases and is often part of an upper respiratory infection.
Diagnose acute bronchitis mainly by clinical evaluation; chest radiographs and/or other tests should be performed in patients who have manifestations of more serious illness or symptoms that are non-resolving or worsening over time.
Treat most patients symptomatically.
