# Croup > Croup for FMGE Paediatrics: barking cough with stridor, dexamethasone dose, nebulised adrenaline, and the epiglottitis differential. - Canonical URL: https://prepelephant.com/topics/fmge/paediatrics/croup-fmge - Exam / course: FMGE · Subject: Paediatrics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Croup", PrepElephant, https://prepelephant.com/topics/fmge/paediatrics/croup-fmge ## 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.