Croup

Croup (laryngotracheobronchitis) — a viral upper airway infection. See also resp symptoms in children and epiglottitis (the key differential).

Clinical features

Characteristic harsh, barking (“dog bark”/“seal bark”) inspiratory cough with stridor; a 2-day URTI prodrome; ages 6 months–6 years; fever variable. Typically presents 11pm–2am (reduced overnight cortisol). Auscultation confirms inspiratory stridor.

Aetiology

Parainfluenza (most common); other viruses including RSV.

Clinical grading

Grade	Features
Mild	No stridor at rest; mild retractions or tachycardia
Moderate	Stridor at rest with sternal/chest wall retractions, accessory muscle use, tachycardia
Severe	Marked respiratory distress — irritability, pallor, cyanosis, tachycardia, exhaustion

Children with Down syndrome or pre-existing upper airway narrowing are at risk of more severe croup.

Management

• Mild: stat oral prednisolone 1 mg/kg, or dexamethasone 0.15 mg/kg — low-dose dexamethasone (0.15 mg/kg) is as effective as higher doses (0.3–0.6 mg/kg).
• Moderate: hospital; dexamethasone (or prednisolone) ± nebulised adrenaline if needed. Nebulised budesonide adds no benefit over oral dexamethasone alone — don’t routinely combine them; either is an effective single-agent option.
• Severe: hospital; nebulised adrenaline (1:1000, 5 mL) plus dexamethasone IV/IM/oral; may need intubation.