What are the key clinical features that differentiate acute bronchitis

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Key clinical features differentiating acute bronchitis from pneumonia in adults:

Acute bronchitis typically presents as an acute illness with cough as the main symptom, lasting up to 3-4 weeks, often accompanied by other lower respiratory tract symptoms such as sputum production, wheeze, or chest discomfort, but without systemic signs of severe illness or focal chest signs on examination ,.
In contrast, pneumonia usually presents with more severe symptoms including fever, productive cough, breathlessness, and chest pain, often with focal chest signs such as crackles or bronchial breathing on auscultation, and systemic features like tachypnoea (respiratory rate ≥30/min), tachycardia (>100 bpm), low blood pressure (systolic <90 mmHg), hypoxia (oxygen saturation <90% on room air), or altered mental status ,.
Severity scores such as CRB65 are used in pneumonia to assess risk and guide management, reflecting the presence of confusion, raised respiratory rate (≥30 breaths/min), low blood pressure, and age ≥65 years, which are not features of uncomplicated acute bronchitis ,.
Acute bronchitis is generally self-limiting and does not require antibiotics unless there is an underlying airway disease or systemic illness, whereas pneumonia requires prompt antibiotic treatment guided by clinical assessment and sometimes CRP levels ,.

What are the key clinical features that differentiate acute bronchitis from pneumonia in adults?