Differentials for croup
Introduction
Croup (acute viral laryngotracheobronchitis) is a common cause of inspiratory stridor in young children, classically producing a “barking” cough, hoarseness and varying degrees of respiratory distress from subglottic oedema.
Several other upper‑airway conditions can mimic croup but require different immediate actions (airway protection, antibiotics, ENT/anaesthesia involvement). Rapid recognition of the common alternatives and their distinguishing features is essential in the ED (RCEMLearning).
Quick differential checklist (ED priorities)
- Typical viral croup (parainfluenza and other respiratory viruses)
- Bacterial tracheitis (often Staphylococcus aureus)
- Epiglottitis (rare since Hib vaccination)
- Foreign‑body airway obstruction
- Anaphylaxis with laryngeal oedema
- Retropharyngeal or peritonsillar abscess
- Diphtheria (rare in vaccinated populations)
- Lower‑airway disease that may cause stridor or severe respiratory distress (severe bronchiolitis, wheeze)
(RCEMLearning; GOV.UK)
Key distinguishing features
The table below summarises features that most help separate viral croup from epiglottitis and bacterial tracheitis in emergency practice.
Note: bacterial tracheitis often follows a viral prodrome of a few days and can initially look like croup; failure to respond to usual croup therapy is a key red flag (RCEMLearning).