Croup vs Epiglottitis: How to Tell Them Apart
Croup and epiglottitis both produce upper-airway obstruction with stridor in children, and both can threaten the airway. The core axis that separates them is tempo and toxicity: croup is a gradual, viral, barky-cough illness in a non-toxic toddler, whereas epiglottitis is a rapid, high-fever, toxic-appearing emergency with drooling and a tripod posture that demands immediate airway protection.
How to tell them apart
| Feature | Croup | Epiglottitis |
|---|---|---|
| Onset | Gradual over days, preceded by a viral URI prodrome | Rapid, over hours |
| Fever | Low-grade | High, often >39°C |
| Cough | Prominent barky, seal-like cough | Minimal or absent cough |
| Drooling/dysphagia | Absent | Present — drooling and dysphagia |
| Position | Comfortable in any position | Tripod position (leaning forward, neck extended) |
| Appearance | Non-toxic | Toxic and anxious |
| Age | Classic 6 months to 3 years | Any age, but classic 2–7 years |
| Voice | Barky cough dominates; voice not classically muffled | "Hot potato" or muffled voice |
| X-ray finding | Steeple sign (subglottic narrowing) on frontal neck film | Thumbprint sign (swollen epiglottis) on lateral neck film |
| Management | Dexamethasone; racemic epinephrine if severe | Do NOT examine the throat or agitate the child; secure the airway first, then IV antibiotics |
The reasoning
Anchor on tempo and toxicity. A toddler with a several-day URI prodrome, low-grade fever, a prominent seal-like barky cough, and a comfortable non-toxic appearance is croup — treat with dexamethasone, adding racemic epinephrine if severe. In contrast, a child with rapid onset over hours, high fever, drooling/dysphagia, muffled 'hot potato' voice, minimal cough, and a toxic, anxious child sitting in the tripod position is epiglottitis. The presence of drooling and a toxic appearance is the strongest arbiter toward epiglottitis; the presence of a barky cough in a well-appearing child arbitrates toward croup. Imaging supports the distinction (steeple sign in croup, thumbprint sign in epiglottitis) but should never delay airway management in a child who looks toxic.
Key tests
- Lateral neck X-ray: thumbprint sign (swollen epiglottis) indicates epiglottitis; a normal epiglottis without this finding argues against it
- Frontal neck X-ray: steeple sign (subglottic narrowing) supports croup
- Clinical airway assessment: barky cough with inspiratory stridor and non-toxic appearance points to croup, whereas drooling, muffled voice, tripod positioning, and toxic appearance point to epiglottitis
What they share
- Both are pediatric upper-airway conditions that present with inspiratory stridor
- Both can cause airway obstruction and are managed as potential airway emergencies
- Both may present with respiratory distress and worsening with agitation
Pitfalls
- Do NOT examine the throat or agitate a child with suspected epiglottitis — this can precipitate complete airway obstruction; keep the child calm and call anesthesia/ENT to secure the airway first
- Although Hib vaccination has made classic Hib epiglottitis rare, it still occurs from S. aureus, S. pneumoniae, and S. pyogenes — do not exclude epiglottitis based on vaccination status
- Do not delay definitive airway management to obtain neck X-rays in a toxic-appearing child; imaging is confirmatory, not a substitute for clinical judgment
- Both cause stridor, so relying on stridor alone will mislead — differentiate using cough, drooling, fever height, and overall toxicity
Practice this the way the exam tests it — on branching cases where your decisions shape the patient.