Croup
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Direct answer
A seal-like barking cough with hoarse voice and inspiratory stridor in a child between six months and three years, typically worsening at night after two days of coryza, is viral croup (laryngotracheobronchitis), most often parainfluenza virus type 1. Dexamethasone 0.15-0.6 mg/kg as a single oral or intramuscular dose is given to every case — mild ones included — because it prevents intubation and rebound; moderate-to-severe croup adds nebulised adrenaline (1:1000) at 0.5 mL/kg, maximum 5 mL, which buys one to two hours of airway while the steroid works. The examination payoff is recognising what croup is not: the drooling, toxic child with a thumb-sign epiglottitis moves to a theatre airway, never a tongue depressor.
What you must remember
- Clinical core: barking cough, inspiratory stridor, hoarseness, low-grade fever, night-time worsening; symptoms peak on day two to three; recurrent afebrile episodes with sudden nocturnal onset in an atopic child suggest spasmodic croup.
- Dexamethasone 0.15-0.6 mg/kg once (0.15 mg/kg is adequate for mild croup), oral route preferred, works within 30 minutes to six hours and cuts hospitalisation and return rates.
- Nebulised adrenaline (racemic or 1:1000 L-adrenaline) 0.5 mL/kg up to 5 mL for moderate-severe croup or stridor at rest; effect begins within 10-30 minutes and lasts one to two hours — observe for at least two to four hours after dosing for rebound.
- Severity (Westley score): stridor at rest, recession, agitation, cyanosis and level of consciousness scored; inspiratory stridor only on agitation is mild, stridor at rest with recession moderate, and agitation, drowsiness or cyanosis severe.
- Epiglottitis red lines: high fever, drooling, muffled voice, tripod posture, minimal cough, rapid toxic deterioration — classically Haemophilus influenzae type b in the unimmunised; keep the child calm, never examine the throat, secure the airway in theatre with a smaller-than-predicted tube.
- Bacterial tracheitis: high fever, toxic appearance, croupy cough that fails steroid therapy, pseudomembrane on bronchoscopy — Staphylococcus aureus; needs airway protection and anti-staphylococcal cover.
- Other look-alikes with one-line discriminators: inhaled foreign body (sudden onset, choking, afebrile, often unilateral signs), diphtheritic laryngitis (bull neck, grey membrane, palatal palsy, immunisation history), retropharyngeal abscess (stiff neck, dysphagia, drooling).
- Stridor physics: inspiratory stridor implies extrathoracic obstruction (larynx), biphasic stridor a subglottic or tracheal lesion (croup, subglottic stenosis), expiratory stridor intrathoracic obstruction — a favourite mapping question.
One night in the emergency department
A two-year-old is brought in at 2 a.m. with a bark-like cough that frightens the parents more than the fever; he has stridor when he cries but settles to soft stridor at rest with subcostal recession and holds his head slightly forward, alert and drinking from a bottle. Westley items grade him moderate. Give dexamethasone 0.6 mg/kg orally and nebulised adrenaline 0.5 mL/kg of 1:1000 by mask while he sits on his mother's lap — separating a toddler from the parent worsens obstruction. Reassess at 30 minutes and again at two hours: if stridor returns to agitation-only and he feeds, discharge with clear instructions. Escalate to intensive care if drowsiness replaces restlessness, stridor softens with rising recession or saturation falls — intubate pre-emptively with a tube one size smaller, by the most experienced hands. The counter-case the same night: an unimmunised four-year-old, febrile to 39.5°C, sitting still, drooling, refusing to speak — epiglottitis until proven otherwise, straight to theatre, no tongue depressor anywhere near.
How the FMGE frames it
Almost every croup question is a differential-disguise. The stem with drooling and tripod posture wants epiglottitis; the stem with sudden choking in an afebrile playing child wants foreign body; the stem with membrane and bull neck wants diphtheria; the "croup not responding to steroids, now toxic with pseudomembrane" stem wants bacterial tracheitis. When the question is genuinely about croup, it wants two numbers — dexamethasone 0.15-0.6 mg/kg once, and adrenaline 0.5 mL/kg (max 5 mL) of the 1:1000 solution nebulised — plus the mechanism: adrenaline's alpha-adrenergic vasoconstriction shrinks subglottic oedema at the narrowest point of a child's airway.
Frequently asked questions
What is the drug treatment for croup?
A single dose of dexamethasone 0.15-0.6 mg/kg orally or intramuscularly for every child with croup, with nebulised adrenaline 0.5 mL/kg (maximum 5 mL) of 1:1000 solution added for moderate or severe cases.
How do croup and epiglottitis differ at the bedside?
Croup gives a barking cough, hoarseness and inspiratory stridor in a less-toxic toddler; epiglottitis gives high fever, drooling, muffled voice, tripod posture and toxicity with minimal cough — and demands airway security without throat examination.
Why does nebulised adrenaline work in croup?
Alpha-adrenergic vasoconstriction reduces subglottic mucosal oedema within minutes; the effect lasts one to two hours, so children must be observed for rebound after the dose.
What is spasmodic croup?
Recurrent, sudden nocturnal episodes of barking cough and stridor in afebrile, often atopic children that resolve quickly — treatment is the same dexamethasone dose, with a search for triggers.
Which organism most commonly causes viral croup?
Parainfluenza virus type 1, followed by other parainfluenza types, respiratory syncytial virus, influenza and adenovirus.