ACUTE BRONCHITIS

✓ Medically ReviewedDISEASEID: MDBT0182🚨 TRIAGE: ROUTINEICD-10: J20.9

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Definition

CLINICAL DEFINITION

Acute bronchitis is a self-limiting inflammatory condition of the large airways (bronchi and trachea) characterised by a cough lasting between one and three weeks, in the absence of pneumonia or other underlying respiratory pathology.

IN PLAIN ENGLISH

Acute bronchitis is a temporary swelling and irritation of the main airways in the lungs, usually caused by a viral infection, which leads to a persistent cough that may produce mucus.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Acute bronchitis is NOT pneumonia; it does not involve infection or consolidation of the lung alveoli. It is also distinct from chronic bronchitis, which is defined by a productive cough lasting for at least three months a year over two consecutive years and is a feature of chronic obstructive pulmonary disease (COPD).

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Word Breakdown

bronch-

=windpipe or airway (from Greek 'bronkhos')

-itis

=inflammation (from Greek '-itis')

Literal Meaning: Inflammation of the bronchi

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Synonyms & Variants

Tracheobronchitis›Chest cold›

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Category-Specific Context

As a disease, acute bronchitis represents a transient inflammatory syndrome of the lower respiratory tract. It is classified primarily by its duration (acute, typically less than three weeks) and the absence of parenchymal lung involvement (pneumonia), distinguishing it from chronic airway diseases.

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Clinical Context & Usage

CLINICAL SETTINGS

General PracticeEmergency DepartmentUrgent Care CentreOutpatient Respiratory Clinic

USAGE & DOCUMENTATION NOTES

In clinical documentation, 'acute bronchitis' is typically recorded as the primary diagnosis when a patient presents with an acute, persistent cough without clinical or radiographic evidence of pneumonia. It is often documented alongside terms like 'viral lower respiratory tract infection' or 'acute tracheobronchitis.' Clinicians frequently note the duration of the cough and the absence of focal chest signs to justify the decision to withhold antibiotics.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Acute bronchitis is primarily caused by viral infections (such as rhinovirus, respiratory syncytial virus, influenza, and coronavirus) that infect the epithelial cells of the tracheobronchial tree. The infection triggers a local inflammatory response, leading to oedema, increased mucus production, and impaired ciliary clearance. This inflammation and airway hyperreactivity stimulate cough receptors, resulting in the hallmark persistent cough. In some cases, transient bronchospasm may occur, mimicking mild asthma. Bacterial causes are rare but can involve Mycoplasma pneumoniae, Chlamydia pneumoniae, or Bordetella pertussis.

PRIMARY CAUSES

Viral infections (Rhinovirus, Coronavirus, Influenza A and B, Parainfluenza, RSV)

Viral replication in the respiratory epithelium triggers local inflammation, mucosal oedema, and increased mucus secretion, leading to airway irritation and cough.

Bacterial infections (Bordetella pertussis, Mycoplasma pneumoniae, Chlamydia pneumoniae)

Less common bacterial pathogens cause direct epithelial damage and prolonged inflammatory responses, often leading to a more protracted cough (e.g., whooping cough).

Environmental irritants (Tobacco smoke, air pollution, chemical fumes)

Inhalation of noxious substances causes non-infectious acute irritation and inflammation of the bronchial mucosa.

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Epidemiology

Prevalence:Acute bronchitis is one of the most common reasons for primary care consultations, affecting approximately 5% of adults annually in temperate climates, with higher incidence during the autumn and winter months.

Age Group:All age groups are affected, but it is most frequently diagnosed in young children and adults aged 18–40 years.

Sex Predilection:Equal

Geographic Distribution:Globally distributed with seasonal peaks in temperate climates during colder months; incidence may be higher in areas with significant indoor air pollution or high rates of tobacco smoking.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 ROUTINE

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Elderly or immunocompromised patients presenting with cough and subtle systemic signs (e.g., confusion, mild hypoxia, or absence of fever) — consider atypical pneumonia or early sepsis, requiring a lower threshold for chest radiography and urgent evaluation.
Prolonged paroxysmal cough with post-tussive emesis or inspiratory whoop in an unimmunised or partially immunised individual — suspect Bordetella pertussis (whooping cough), which requires specific macrolide therapy and public health notification.

URGENT EVALUATION TRIGGERS

Heart rate > 100 beats per minute or respiratory rate > 24 breaths per minute in an adult
Oxygen saturation < 94% on room air
Focal chest signs on auscultation (e.g., coarse crackles, bronchial breathing, or dullness to percussion)
Haemoptysis (coughing up blood) or severe pleuritic chest pain
Altered mental status or signs of severe systemic toxicity

Contraindications & Precautions

SPECIAL PRECAUTIONS

Exercise caution when prescribing antitussives (e.g.
codeine
dextromethorphan) in children and the elderly due to the risk of respiratory depression or inadequate clearance of secretions.
Monitor patients with underlying cardiopulmonary disease (e.g.
heart failure
COPD) closely
as they are at higher risk for complications or misdiagnosis of a more severe exacerbation.

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Post-infectious cough — airway hyperreactivity and epithelial damage can cause a cough to persist for 3–8 weeks after the initial infection resolves.
Secondary bacterial pneumonia — rarely
the initial viral infection or impaired mucociliary clearance can predispose the patient to a secondary bacterial infection of the lung parenchyma.
Exacerbation of underlying airway disease — can trigger severe exacerbations in patients with pre-existing asthma or chronic obstructive pulmonary disease (COPD).

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Bronchiolitis

Sounds similar and both involve lower respiratory tract inflammation; however, bronchiolitis affects the small airways (bronchioles) and primarily occurs in infants under 2 years of age.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Pneumonia

Key Distinguishing Feature: Presence of systemic signs (high fever, tachycardia), focal chest signs (crackles, bronchial breathing, dullness to percussion), and infiltrates on chest radiograph.

Asthma exacerbation

Key Distinguishing Feature: History of recurrent wheeze, personal or family history of atopy, and widespread polyphonic wheeze on auscultation that responds to bronchodilators.

Post-nasal drip syndrome (Upper airway cough syndrome)

Key Distinguishing Feature: Sensation of fluid dripping in the back of the throat, frequent throat clearing, and cobblestone appearance of the posterior pharynx.

Gastro-oesophageal reflux disease (GORD)

Key Distinguishing Feature: Cough is often worse at night or after meals, accompanied by heartburn or acid regurgitation, without infectious prodrome.

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Clinical Pearls

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Acute bronchitis is a clinical diagnosis of exclusion for pneumonia; in the absence of abnormal vital signs (tachycardia, tachypnoea, hypoxia, high fever) or focal chest findings, a chest X-ray is not routinely indicated.

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The cough of acute bronchitis typically lasts for 1–3 weeks. Patients should be reassured that a prolonged cough is a normal part of the post-infectious inflammatory recovery process and does not automatically signify treatment failure or the need for antibiotics.

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Routine antibiotic therapy is strongly discouraged for acute bronchitis in otherwise healthy adults, as it provides minimal reduction in symptom duration and significantly increases the risk of adverse effects and antimicrobial resistance.

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Consider a trial of a short-acting beta-agonist (e.g., salbutamol) only if the patient exhibits wheezing or underlying airway hyperreactivity; it is not routinely beneficial for cough without bronchospasm.

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Example Usage & SOAP

CLINICAL SENTENCE

"The patient presents with a 10-day history of a productive cough and mild coryza; examination reveals clear lung fields bilaterally with no focal signs of consolidation, consistent with acute viral bronchitis."

IN A SOAP NOTE

S: 32-year-old female presents with a 7-day history of worsening cough, initially dry but now producing clear sputum. Reports mild fatigue and a sore throat, but denies fever, shortness of breath, or chest pain. O: Temp 37.1°C, HR 78 bpm, RR 14/min, SpO2 98% on room air. Chest auscultation reveals transmitted upper airway sounds but no focal crackles, wheeze, or bronchial breathing. A: Acute bronchitis, likely viral aetiology. No clinical signs suggestive of pneumonia. P: Reassurance regarding the expected 2–3 week duration of the cough. Advised supportive care with hydration, honey, and paracetamol for symptomatic relief. Antibiotics withheld. Safety-netted to return if symptoms worsen, fever develops, or shortness of breath occurs.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for acute cough (1-3 weeks): (1) Acute bronchitis — characterised by cough without focal chest signs or systemic toxicity; (2) Pneumonia — suspected if tachypnoea, tachycardia, fever, or focal crackles/bronchial breathing are present; (3) Asthma exacerbation — considered if there is a history of atopy, nocturnal symptoms, or polyphonic wheeze; (4) Post-nasal drip — suggested by throat clearing and nasal symptoms; (5) Pertussis — suspected if the cough is paroxysmal with post-tussive emesis.

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Prognosis

SHORT-TERM OUTCOME

Generally excellent; the acute infectious symptoms resolve within a few days, though the cough typically persists for 1–3 weeks.

LONG-TERM PROGNOSIS

No long-term sequelae in otherwise healthy individuals; complete recovery of airway epithelium and ciliary function is expected. Does not progress to chronic bronchitis.

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References & Coding

ICD-10 DIAGNOSTIC CODE

J20.9

LITERATURE CITATIONS & GUIDELINES

[1]Wenzel RP, Fowler AA. Acute bronchitis. N Engl J Med. 2006;355(22):2325-2329. doi:10.1056/NEJMcp061493

[2]Smith SM, Fahey T, Smucny J, Becker LA. Antibiotics for acute bronchitis. Cochrane Database Syst Rev. 2017;6(6):CD000245. doi:10.1002/14651858.CD000245.pub4

[3]National Institute for Health and Care Excellence (NICE). Respiratory tract infections (self-limiting): prescribing antibiotics. NICE guideline [NG69]. 2008 (updated 2017).

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.