Croup

Overview & Definition

Croup (acute laryngotracheobronchitis) is an acute viral upper airway infection producing inflammation and oedema of the larynx, trachea, and bronchi, with the dominant obstruction located in the subglottic region (just below the vocal cords, encircled by the cricoid cartilage). It is the most common cause of acute stridor in febrile children between 6 months and 6 years of age, and one of the most frequent reasons for emergency department attendance and hospital admission in early childhood. The clinical syndrome is defined by its triad of barking (seal-like) cough, harsh inspiratory stridor, and hoarse voice, often preceded by 1 to 2 days of coryza and low-grade fever, with symptoms characteristically worse at night.^[1][2]

The vast majority of cases are mild and self-limiting, resolving within 3 to 7 days. A small but clinically important fraction progress to moderate or severe disease with significant respiratory compromise, and a tiny minority (under 0.5 percent) require intubation. The disorder sits in a narrow diagnostic space shared with several immediately life-threatening mimics — epiglottitis, bacterial tracheitis, retropharyngeal abscess, and foreign body aspiration — and the central clinical skill is to distinguish the common, benign, self-limiting viral croup from these conditions whose management is fundamentally different and time-critical. The single most important therapeutic advance of the last 30 years has been the recognition that a single dose of oral dexamethasone benefits children with croup of any severity, including those traditionally labelled "mild".^[1][3]

Classification

Croup is classified by severity, using either the full Westley croup score (the validated research and clinical tool) or a simplified bedside assessment based on stridor at rest, work of breathing, and oxygenation. Severity directly drives the treatment ladder — the decision to give adrenaline, admit, or discharge hangs on this classification.^[1]

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Epidemiology & Risk Factors

Croup is overwhelmingly a disease of early childhood, accounting for around 3 to 5 percent of all children each year and representing one of the leading causes of paediatric emergency attendance and hospital admission. Annual incidence is approximately 6 per 100 children under 6 years in primary care; around 1 to 5 percent of all croup presentations require hospitalisation, and 0.5 to 2 percent of hospitalised children need intensive care. Intubation is required in fewer than 0.5 percent of hospital cases, and death is now rare (under 0.5 percent mortality in intubated children) in countries with modern PICU and safe airway management.^[1][2]

The epidemiology follows the circulation of parainfluenza virus type 1, which produces characteristic biennial autumn epidemics in alternate (odd-numbered) years in many temperate countries; parainfluenza type 2 produces smaller, more sporadic outbreaks; parainfluenza type 3 circulates annually and tends to cause bronchiolitis and pneumonia as well as croup at younger ages. Risk factors include age 6 months to 3 years (the age at which the subglottic airway is smallest relative to airflow demand), autumn and winter season, prior episode of croup (recurrence is common), male sex, prematurity, attendance at daycare, and parental smoking. Recurrent croup (more than 2 to 3 episodes in 6 months) or atypical age (under 6 months or over 6 years) should prompt consideration of an underlying anatomical abnormality — subglottic stenosis (post-intubation), subglottic haemangioma, laryngeal web, laryngomalacia — or gastro-oesophageal reflux and airway hyper-reactivity/atopy, and warrants ENT referral for flexible laryngoscopy and bronchoscopy.^[1][10]

Pathophysiology

Croup begins when a respiratory virus — overwhelmingly parainfluenza virus type 1 (around 50 to 75 percent of cases), followed by parainfluenza type 2 and 3, influenza A and B, respiratory syncytial virus (RSV), adenovirus, rhinovirus, enterovirus, human metapneumovirus, and occasionally measles in unvaccinated populations — infects the ciliated respiratory epithelium of the nasopharynx and then the larynx, trachea, and bronchi.^[1][10]

The resulting mucosal inflammation, vascular congestion, increased mucus production, and fibrinous exudate produce the characteristic subglottic oedema. The cricoid cartilage — the only complete cartilaginous ring of the trachea, lying at the level of the sixth cervical vertebra in adults but more cephalad in infants — cannot expand outward to accommodate the swelling, so the oedema is forced inward into the airway lumen.^[11] The subglottic region is also the functionally narrowest segment of the paediatric airway (rather than the glottis, as in adults), so any narrowing here has disproportionate effects.

The clinical consequences are governed by the physics of laminar flow through a tube: by Poiseuille's law, airway resistance is inversely proportional to the fourth power of the radius (resistance proportional to 1 over radius to the fourth power). A small reduction in airway radius therefore produces a large increase in resistance. In a neonate the subglottic lumen is approximately 4 to 5 mm; just 1 mm of circumferential oedema reduces the cross-sectional area by roughly 75 percent and multiplies resistance many-fold. In a toddler the airway is wider but the same principle applies: small changes in oedema, mucous plugging, or agitation produce large swings in work of breathing. This is why croup symptoms fluctuate hour to hour, worsen with crying and agitation (which increase airflow turbulence and dynamic collapse), improve with cool humidified air and corticosteroids (which reduce mucosal oedema), and characteristically peak at night.^[1][2]

The barking cough arises from inflammation of the subglottis and vocal cords; the hoarse voice reflects vocal cord involvement; and the stridor is generated by turbulent airflow through the narrowed subglottis. Stridor is inspiratory when obstruction is extrathoracic (at the level of the larynx or subglottis, as in croup) because the negative intrathoracic pressure of inspiration pulls the soft extrathoracic airway inward and narrows it further; biphasic stridor suggests a fixed or more severe obstruction.^[1][2]

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Clinical Presentation

The classic presentation is a child aged 6 months to 6 years (peak 1 to 2 years) who develops 1 to 2 days of coryza, low-grade fever, and mild cough, followed by the abrupt onset of a barking (seal-like) cough, harsh inspiratory stridor, and hoarse voice, typically worse in the evening and overnight and provoked by crying or distress. The child is usually afebrile or has a low-grade fever (38 to 39 degrees C), looks well between coughing paroxysms, sits upright, and does not drool. The pitch of the cry is often abnormal. Parents frequently describe the cough as sounding "like a seal or a small dog barking" or "as if the child is barking at the moon" — a description so characteristic that a telephone history alone is moderately predictive.^[1][2]

Symptoms follow a characteristic diurnal pattern: worse at night, improving in the morning, worsening again the next night, peaking on days 1 to 2 of illness, and resolving over 3 to 7 days. The cough and stridor fluctuate with the child's state — crying, agitation, and distress all worsen obstruction; calm, parental presence, and cool air improve it.^[1]

^[1]

The child who looks well and is playful between coughing bouts but produces a seal-like bark on crying has mild croup; the child who sits forward, drools, has no cough, and looks toxic has epiglottitis, not croup. This single clinical distinction is the most important one in paediatric upper airway medicine.^[8]

Differential Diagnosis

The differential of stridor and barking cough in a young child is broad, but the immediate clinical task is to separate common, benign, viral croup from the life-threatening mimics that demand a fundamentally different, time-critical response. The cardinal discriminator is toxicity: the child with croup is typically not toxic (or only mildly unwell), whereas the child with epiglottitis, bacterial tracheitis, or a deep neck abscess is toxic, drooling, and rapidly deteriorating.^[1][8]

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The key distinguishing features that rule out uncomplicated croup and demand escalation are: toxicity, high fever (over 39.5 degrees C), drooling, dysphagia, tripod posture, rapid deterioration, no response to adrenaline and dexamethasone, asymmetric chest findings, or a foreign-body history. Any of these should prompt immediate re-evaluation for an alternative diagnosis.^[8][12]

Clinical & Bedside Assessment

Croup is a clinical diagnosis made at the bedside. The history and observation alone usually establish the diagnosis; investigations should be minimal and only performed if the diagnosis is uncertain or the child is severely ill, because agitation from any procedure worsens airway obstruction.^[1]

History should establish: age, onset and duration (gradual over hours to days is typical; abrupt without prodrome suggests foreign body), preceding coryza or viral illness, the character of the cough (bark, seal-like), stridor (present only with crying or also at rest), fever (degree and duration), feeding and hydration, drooling or dysphagia (which suggest epiglottitis), vaccination history (Hib, measles), immunisation, prior episodes of croup, family history of atopy or airway problems, and any chronic conditions. Trigger factors — crying, agitation, cold air, night-time — should be elicited, as should the response to any treatment already given.^[1]

Examination is best performed calmly and at a distance first, allowing the child to remain in the parent's arms. The four cardinal observations are: (1) work of breathing — rate, retractions (suprasternal, intercostal, subcostal), nasal flaring, accessory muscle use, head bobbing in infants; (2) stridor — present at rest, with agitation, or only with crying; (3) oxygen saturation in air; and (4) mental state — alert, anxious, agitated (a sign of hypoxia), or lethargic (a late, ominous sign). The child's position (upright and playing, tripod, or slumped) and skin colour (pink, pale, mottled, or cyanosed) are noted. Auscultation should confirm symmetrical air entry (asymmetry suggests foreign body or pneumonia) and listen for wheeze. Do NOT examine the throat with a tongue depressor if epiglottitis is suspected — this can precipitate complete airway obstruction.^[1][8]

The Westley croup score quantifies severity and should be calculated on every child with croup, both to guide treatment and to document change over time:^[7]

• Stridor: 0 none, 1 when agitated or active, 2 at rest
• Retractions: 0 none, 1 mild, 2 moderate, 3 severe
• Air entry: 0 normal, 1 mildly decreased, 2 markedly decreased
• Cyanosis: 0 none, 4 with agitation, 5 at rest
• Level of consciousness: 0 normal, 5 disoriented^[7][1]

The total (0 to 17) is banded as mild (0 to 2), moderate (3 to 5), severe (6 to 11), and impending respiratory failure (12 to 17).^[7][1]

Investigations

Most croup is a clinical diagnosis, and no investigations are needed for a typical mild or moderate case in an age-appropriate child with a classic history and response to treatment. The principle is first do no harm: agitating a child with croup (by venepuncture, X-ray, or laryngoscopy) worsens the obstruction, so any test should have a clear clinical purpose.^[1]

When investigations are warranted — for severe or atypical disease, an uncertain diagnosis, failure to respond to treatment, or recurrence:^[1]

• Neck X-ray (anteroposterior and lateral) only if the diagnosis is uncertain or to exclude an alternative. The classic finding is the steeple sign (also called the pencil tip sign) on the AP view: a smooth, symmetric, tapered narrowing of the subglottic air column, often several centimetres below the vocal cords, replacing the normal "shoulders" of the subglottis. The lateral view excludes retropharyngeal abscess (prevertebral soft tissue widening greater than 7 mm at C2 or 14 mm at C6 in young children) and epiglottitis (thickened, rounded thumb sign of the epiglottis and swelling of the aryepiglottic folds). The steeple sign is neither sensitive nor specific — it is absent in up to half of confirmed croup and can be seen in other causes of subglottic narrowing (subglottic stenosis, haemangioma) — so it is a confirmatory, not diagnostic, sign.^[1]
• Viral PCR (multiplex respiratory panel or nasopharyngeal aspirate) may identify parainfluenza, RSV, influenza, or other viruses; it does not change management of an individual child but is useful for cohorting in hospital and surveillance.
• Bloods (FBC, CRP, electrolytes, venous blood gas) are reserved for severe disease, toxic appearance, or suspected bacterial superinfection.
• Capillary or arterial blood gas for impending respiratory failure (looking for hypoxaemia, hypercapnia, and acidosis).
• Laryngoscopy / bronchoscopy is not routine in croup; it is reserved for atypical presentations, recurrent or persistent croup, suspected foreign body, or failure to respond to appropriate therapy, and should be performed by an experienced ENT or anaesthetic operator with a secured airway plan, often in theatre.^[1]

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Management — Resuscitation

Severe croup (Westley 6 or above, or any child with stridor at rest, marked retractions, cyanosis, altered consciousness, or SpO2 under 92 percent in air) is a time-critical airway emergency. The aim is to relieve obstruction, reduce oedema, and avoid agitation, which alone can precipitate complete obstruction.^[1]

The resuscitation bundle, applied calmly and without unnecessary intervention, is:^[1][6]

1. Careful clinical assessment first — a careful history and physical examination is the best method to confirm the diagnosis and to rule out potentially serious alternative disorders such as bacterial tracheitis.^[1]
2. Dexamethasone for every child — a single dose of orally administered dexamethasone 0.15 to 0.6 mg/kg is the mainstay of treatment; oral dexamethasone may be the best option because of its ease of administration, widespread availability, and lower cost. If the oral preparation is not tolerated, nebulised budesonide 2 mg or intramuscular dexamethasone are reasonable alternatives.^[15][14][18]
3. Nebulised epinephrine for moderate to severe croup — conventional trial dosing is 1:1000 L-epinephrine 0.5 mg/kg (maximum 5 mg); with dexamethasone 0.6 mg/kg, croup scores fall significantly by 30 minutes, and a low dose of 0.1 mg/kg was not inferior to the conventional dose.^[16][14]
4. Expect the epinephrine effect to be transient — improvement is seen at 30 minutes but is no longer significant at two and six hours, and racemic epinephrine improved scores at 10 and 30 minutes but not at 120 minutes. The effect lasts only about two hours, a rebound effect can occur, and some children treated with adrenaline can be safely discharged after a two to three hour observation period.^[6][7][19]
5. In severe croup and impending respiratory failure — simultaneous administration of corticosteroid and epinephrine reduces the rate of intubation; nebulised epinephrine may prevent intubation.^[18][6]
6. Do not reach for mist — exposure to cold air or administration of cool mist are interventions not supported by published evidence.^[15]

Heliox (helium-oxygen mixture) may be considered as a temporising measure in refractory obstruction: breathing heliox can potentially reduce the work of breathing related to upper airway obstruction, but the evidence base is limited and it is not a substitute for corticosteroids and nebulised epinephrine.^[15]

Suspected epiglottitis — differentiate early with two bedside observations: drooling has high specificity (0.94) for epiglottitis, while coughing is almost universal in croup (sensitivity 1.00); epiglottitis shows drooling with absence of coughing, croup shows coughing with absence of drooling. Epiglottitis has become rare relative to bacterial tracheitis since immunisation against Haemophilus influenzae type b. Treat it as a separate, potentially life-threatening airway emergency requiring immediate senior airway involvement — in reported series these children were managed with intubation in a paediatric intensive care setting.^[8][12]

Suspected bacterial tracheitis — in a 9-year series it has replaced viral croup and epiglottitis as the leading potentially life-threatening upper airway infection: 94 percent required paediatric intensive care admission, 83 percent were intubated, 28 percent developed serious complications, and it was 3 times more likely to have caused respiratory failure than viral croup and epiglottitis combined. Consider bacterial tracheitis in any child presenting with an acute life-threatening upper airway infection, and involve intensive care and senior airway teams early.^[12]

Management — Definitive & Stepwise

The cornerstone of croup management is corticosteroids for every child with croup, regardless of severity. This is supported by multiple Cochrane reviews and large randomised trials showing that a single dose of dexamethasone reduces symptom severity, shortens hospital stay, reduces the need for adrenaline, and reduces return visits — and that the benefit extends even to children traditionally classified as "mild".^[3][4]

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Specific drugs

Dexamethasone is the corticosteroid of choice: a single dose of orally administered dexamethasone 0.15 to 0.6 mg/kg is the mainstay of treatment (the dose may be 0.15 to 0.6 mg/kg by mouth or intramuscular injection), and oral dexamethasone may be the best option because of its ease of administration, widespread availability and lower cost. In most studies 0.6 mg/kg has been used, with some evidence that 0.15 mg/kg is just as effective; a 1252-child noninferiority randomised trial confirmed that low-dose dexamethasone 0.15 mg/kg is noninferior to 0.6 mg/kg, with no clinically significant difference in efficacy or re-attendance.^{[15][14][19][17]}

Nebulised budesonide 2 mg can be given alternatively to children who do not tolerate oral dexamethasone, as can intramuscular dexamethasone; adding budesonide 2 mg on top of oral dexamethasone 0.15 mg/kg offers no advantage. The original three-arm trial in 144 children with moderately severe croup compared nebulised budesonide 4 mg, intramuscular dexamethasone 0.6 mg/kg and placebo: hospitalisation was 71 percent with placebo, 38 percent with budesonide and 23 percent with dexamethasone — both glucocorticoids improved croup scores more than placebo, with dexamethasone offering the greatest improvement.^{[15][18][21][5]}

Prednisolone at 1 mg/kg as a single oral dose has been compared directly with dexamethasone in a 1252-child noninferiority trial: prednisolone was noninferior to dexamethasone 0.6 mg/kg (adjusted difference in Westley score at 1 hour of 0.05; re-attendance 21.7 percent versus 17.8 percent), and the type of oral steroid seems to have no clinically significant impact on efficacy. A separate 226-child trial in children with Westley scores of 2 or more found that 0.15 mg/kg oral dexamethasone reduced the croup score at 4 hours significantly more than prednisolone 1 mg/kg.^[17][20]

Nebulised epinephrine (adrenaline) is reserved for moderate to severe croup. Conventional trial dosing is 1:1000 L-epinephrine 0.5 mg/kg (maximum 5 mg); Klassen's perspective describes L-epinephrine 5 mL of 1:1000 (or racemic epinephrine 0.5 mL) for children with moderate or severe distress, and evidence does not favour racemic epinephrine or L-epinephrine. Onset is fast — racemic epinephrine improved clinical scores at 10 and 30 minutes but not at 120 minutes, and pooled trial data show croup score improvement at 30 minutes that is no longer significant at two and six hours. Because the effect lasts only about two hours and a rebound effect can occur, children treated with adrenaline can be discharged after a two to three hour observation period.^{[16][14][6][7][19]}

Antibiotics are NOT indicated in uncomplicated viral croup. They are reserved for suspected bacterial superinfection (bacterial tracheitis, pneumonia, otitis media) or an alternative bacterial diagnosis.^[1]

Cough suppressants, decongestants, and antihistamines have no role and may cause sedation, which is dangerous in a child with airway obstruction.^[1]

Stepwise management summary

1. Diagnose clinically — inspiratory stridor, barking cough and hoarseness; the diagnosis is mainly clinical and diagnostic studies are usually not necessary.^[18]
2. Assess severity — Westley croup score: mild croup is a score of 2 or less, moderate to severe croup is scores 3 to 11 in trials.^[4][16]
3. Give a single oral dose of dexamethasone 0.15 to 0.6 mg/kg to every child with croup, whatever the severity.^[15][1]
4. Add nebulised epinephrine only for moderate to severe disease — 1:1000 L-epinephrine 0.5 mg/kg (maximum 5 mg).^[15][16]
5. If oral dexamethasone is not tolerated — nebulised budesonide 2 mg or intramuscular dexamethasone.^[15][18]
6. Observe two to three hours after adrenaline before discharge — the effect lasts only about two hours and rebound can occur.^[19]
7. Do not use cool mist or humidification as treatment — not supported by published evidence.^[15][9]
8. Escalate in severe croup and impending respiratory failure — simultaneous corticosteroid and epinephrine reduces the rate of intubation.^[18]

Specific Subtypes & Scenarios

Spasmodic croup (also called "recurrent allergic croup" or "spasmodic laryngitis") describes recurrent, brief (hours) nocturnal episodes of barking cough and stridor in a child who is well between episodes, often atopic (eczema, asthma, family history of atopy), and without fever or viral prodrome. The aetiology is thought to be allergic or viral-triggered laryngeal oedema rather than the classic viral laryngotracheobronchitis. Each episode responds to cool air and a single dose of dexamethasone; recurrent episodes warrant ENT evaluation for an underlying anatomical cause and consideration of reflux and atopy management.^[1][10]

Recurrent croup (more than 2 to 3 episodes in 6 months, or any recurrence with atypical features) should trigger a search for an underlying cause: subglottic stenosis (post-intubation or congenital), subglottic haemangioma, laryngeal web, laryngomalacia, laryngeal cleft, gastro-oesophageal reflux, airway hyper-reactivity, or immunodeficiency. Referral to paediatric ENT for flexible laryngoscopy and bronchoscopy is indicated, and aerodigestive evaluation (including triple endoscopy in selected centres) may identify surgically correctable lesions.^[10]

Atypical age — croup under 6 months or over 6 years is unusual and should prompt the same workup as recurrent croup; congenital airway anomalies (laryngomalacia, subglottic haemangioma, vascular ring) and acquired causes (subglottic stenosis, foreign body) dominate.^[10]

Refractory croup — failure to respond to adrenaline and dexamethasone within 2 to 4 hours, or deterioration despite treatment, is a red flag: reconsider the diagnosis (epiglottitis, bacterial tracheitis, retropharyngeal abscess, foreign body, anatomical lesion), escalate to PICU, and involve senior anaesthetics and ENT.^[1][12]

Croup in a child with an artificial airway history (prematurity, prior intubation, tracheostomy) raises the likelihood of subglottic stenosis and warrants lower threshold for admission and ENT input.^[1]

Measles croup — in unvaccinated children, measles can cause severe, necrotising laryngotracheobronchitis requiring PICU and ENT; consider in areas with falling vaccination coverage, alongside the classic coryza, conjunctivitis, Koplik spots, and descending rash.^[1]

Complications & Pitfalls

Complications are uncommon but potentially life-threatening:^[1][12]

• Respiratory failure — the feared endpoint of progressive obstruction; prevented by early recognition, dexamethasone, and judicious adrenaline.
• Hypoxic neurological injury — rare, in children who arrest or have prolonged severe hypoxaemia.
• Bacterial superinfection — secondary bacterial tracheitis (Staph aureus, Streptococcus), pneumonia, or otitis media may complicate viral croup; suspect with new or persistent fever, toxicity, or purulent secretions.
• Pneumomediastinum and pneumothorax — from the high intrathoracic pressures generated by severe coughing or positive-pressure ventilation; usually self-limiting but pneumothorax may require drainage.
• Dehydration — from reduced oral intake due to increased work of breathing; assess hydration and treat with oral, NG, or IV fluids.
• Pulmonary oedema — after relief of severe upper airway obstruction (negative-pressure pulmonary oedema); recognise and treat with oxygen and diuretics if needed.
• Recurrence — common in atopic children; consider underlying cause if frequent.^[1][12]

Pitfalls in management:^[1][8]

• Mistaking epiglottitis or bacterial tracheitis for croup — the most dangerous error. Any toxic, drooling, tripod, or rapidly deteriorating child needs an alternative diagnosis considered and escalation, not "more croup treatment".
• Delaying corticosteroids — give dexamethasone to every child with croup, even mild; the benefit is established.
• Over-reliance on the steeple sign — it is neither sensitive nor specific; do not require it to make the diagnosis.
• Discharging too soon after adrenaline — rebound occurs; observe at least 2 to 4 hours.
• Agitating the child — crying and struggling worsen obstruction; keep calm, avoid unnecessary procedures, and treat in the parent's arms.
• Using the wrong endotracheal tube — intubating a child with subglottic oedema with an age-predicted tube size risks trauma; use a tube 0.5 to 1.0 mm smaller.
• Missing recurrent croup — investigate recurrent or atypical presentations for underlying anatomical causes.^[1][8]

Prognosis & Disposition

The prognosis of croup is excellent with appropriate treatment. Most children recover fully within 3 to 7 days, with symptoms peaking on days 1 to 2 and improving thereafter. Hospitalisation is needed in 1 to 5 percent of presentations, intensive care in 0.5 to 2 percent of hospitalised cases, and intubation in fewer than 0.5 percent. Mortality is now very low in countries with modern PICU care — historically under 0.5 percent of intubated children — and is essentially confined to children with significant comorbidity, delayed presentation, or alternative diagnoses (epiglottitis, bacterial tracheitis) mistaken for croup.^[1]

Disposition is determined by severity, response to treatment, age, comorbidity, and social factors:^[1]

Discharge criteria are: no stridor at rest, no significant retractions, normal air entry, normal mental state, SpO2 over 92 percent in room air, tolerating oral fluids, and at least 2 to 4 hours since the last dose of adrenaline (to detect rebound). Parents must be given a clear written safety-net covering warning signs and when to return.^[1]

Special Populations

Infants under 6 months: croup is uncommon in this age group and an atypical presentation should prompt consideration of congenital airway anomalies (laryngomalacia, subglottic haemangioma, laryngeal web, vascular ring), germ-layer defects, or subglottic stenosis from prior intubation. Admit for observation, oxygen, and ENT referral; have a lower threshold for airway intervention.^[1]

Older children (over 6 years): croup is uncommon and should raise suspicion of anatomical causes (subglottic stenosis, laryngeal polyps), foreign body, malignancy, or bacterial tracheitis. Investigate and involve ENT.^[1]

Children with asthma or atopy: more likely to have recurrent croup and spasmodic features; co-treatment with bronchodilators if wheeze is present; the principles of croup management (dexamethasone, adrenaline) are unchanged.^[10]

Immunocompromised children: longer and atypical viral courses, broader differentials (CMV, fungal, mycobacterial), higher risk of secondary infection; admit and involve microbiology and immunology.^[1]

Children with chronic lung disease, congenital heart disease, or neuromuscular disorders: lower threshold for admission and HDU; these children tolerate respiratory compromise poorly.^[1]

Pregnant adolescent or adolescent mother: management is the same; ensure adolescent-friendly setting, contraception and safeguarding review as appropriate.^[1]

Evidence, Guidelines & Regional Differences

The evidence base for croup management is strong and remarkably consistent across guidelines.^[3]

Corticosteroids: the Cochrane review (Russell 2011) included 38 studies (n = 4299) and found glucocorticoids improved the Westley score (maximum 17 points) at six hours (mean difference -1.2) and 12 hours (-1.9) with no significant improvement at 24 hours, produced fewer return visits and/or (re)admissions (risk ratio 0.5), shortened time in accident and emergency or hospital by about 12 hours, and decreased the use of epinephrine; dexamethasone and budesonide relieve symptoms as early as six hours after treatment.^[3] The landmark Bjornson 2004 NEJM trial randomly assigned 720 children with mild croup (Westley score of 2 or less) to one oral dose of dexamethasone 0.6 mg/kg or placebo: return to medical care fell from 15.3 to 7.3 percent, with quicker resolution of symptoms, less lost sleep and less parental stress — establishing the principle that corticosteroids are for children with mild croup too, not just severe cases.^[4]

Nebulised budesonide was tested by Johnson 1998 NEJM in 144 children with moderately severe croup: a single 4 mg nebulised dose versus intramuscular dexamethasone 0.6 mg/kg versus placebo reduced hospitalisation to 38 percent (budesonide) and 23 percent (dexamethasone) from 71 percent with placebo — both glucocorticoids improved croup scores more than placebo, with dexamethasone offering the greatest improvement. The 2 mg nebulised dose is the established alternative for children who cannot take oral medication, though oral dexamethasone is as effective, easier to administer and cheaper.^[5][19]

Nebulised adrenaline: the Cochrane review (Bjornson 2013) confirmed that nebulised adrenaline produces rapid (within 30 minutes) symptomatic improvement in moderate to severe croup compared with placebo, but the effect is short-lived (1 to 2 hours), with rebound after the drug wears off — hence the need for observation.^[6] The original Westley 1978 study established racemic epinephrine (and the Westley score itself) for croup.^[7]

Humidified air / mist therapy: the Cochrane review (Moore 2011, later withdrawn for updates) found no evidence of benefit for humidified or cool mist therapy in croup; many units still use it for comfort but it should not be presented as evidence-based.^[9]

Antibiotics: no role in uncomplicated viral croup.^[1]

Controversies include the optimal dexamethasone dose (0.15 versus 0.6 mg/kg — a 1252-child noninferiority trial found 0.15 mg/kg noninferior to 0.6 mg/kg), the epinephrine dose (a low dose of 0.1 mg/kg 1:1000 L-epinephrine was not inferior to the conventional 0.5 mg/kg), the choice of oral steroid (prednisolone 1 mg/kg was also noninferior to dexamethasone), the role of heliox (breathing heliox can potentially reduce the work of breathing related to upper airway obstruction, but evidence is limited), and mist therapy (exposure to cold air or cool mist is not supported by published evidence).^[17][16][15]

Exam Pearls

^{[18] [14] [6] [15]}

• Croup = parainfluenza virus (majority of cases), age 6 months to 6 years, barking cough + inspiratory stridor + hoarseness; symptoms usually resolve within 48 hours.^[18][13]
• Dexamethasone 0.15 to 0.6 mg/kg orally, single dose, for every child with croup — including mild disease (0.6 mg/kg in the 720-child mild-croup trial; 0.15 mg/kg noninferior in a 1252-child trial).^[15][4][17]
• Nebulised epinephrine is reserved for moderate to severe disease — 1:1000 L-epinephrine 0.5 mg/kg (maximum 5 mg), or L-epinephrine 5 mL of 1:1000; improvement at 30 minutes that is no longer significant at two and six hours; rebound can occur, so discharge only after two to three hours of observation.^{[18][16][14][6][19]}
• Westley croup score (0 to 17): mild croup was defined as a score of 2 or less in trials; moderate to severe croup as scores of 3 to 11.^[4][16]
• Epiglottitis versus croup: drooling is highly specific (0.94) for epiglottitis and coughing is almost universal (sensitivity 1.00) in croup — differentiate early by observing cough and drooling.^[8]
• Bacterial tracheitis has eclipsed viral croup and epiglottitis as the leading life-threatening upper airway infection: 94 percent needed paediatric intensive care and 83 percent were intubated — consider it in any child with an acute life-threatening upper airway infection.^[12]
• Recurrent croup: a viral pathogen was detected in 68 percent of admitted children, with no difference between single-episode and recurrent croup — the aetiologies appear similar, and the traditional viral versus spasmodic distinction often cannot be made.^[10][19]
• Humidified air / cool mist: not supported by published evidence — corticosteroids benefit children with all levels of severity of croup, including mild cases.^[15][1]

Exam application bank (NEET-PG / INICET)

One-line answer

Croup (acute laryngotracheobronchitis) is a common cause of acute upper airway obstruction in young children, usually between the ages of 6 months and 3 years, and about 75 percent of infections are caused by parainfluenza virus. Presentation: abrupt onset, most commonly at night, of barking cough, inspiratory stridor and hoarseness; symptoms usually resolve within 48 hours. Treatment: a single oral dose of dexamethasone 0.15 to 0.6 mg/kg for every child with croup; nebulised epinephrine (1:1000 L-epinephrine 0.5 mg/kg, maximum 5 mg) reserved for moderate to severe disease, with two to three hours of observation before discharge because the effect lasts only about two hours and rebound can occur. ^{[13][15][16][19]}

Worked stems (answer without another resource)

Stem 1 — Classic presentation. Map symptoms to mechanism; name the first investigation and first treatment step with dose/route if drug therapy is standard. ^[1]

Stem 2 — Unstable / complicated. List red flags that force immediate resuscitation, theatre, ICU, antidote, or reperfusion — and what you do in the first 15 minutes. ^[1]

Stem 3 — Atypical group. Elderly, pregnancy, child, or immunocompromised: how presentation and thresholds change. ^[1]

Stem 4 — Differential trap. Name the three closest mimics and one discriminator for each. ^[1]

Stem 5 — Disposition. Who goes home with safety-netting, who is admitted, who needs HDU/ICU/theatre, and what follow-up is mandatory. ^[1]

Rapid viva checklist

1. Definition + classification
2. Pathophysiology chain
3. Bedside signs / criteria
4. Score with exact components (if any)
5. Emergency bundle
6. Definitive therapy with doses
7. Complications of disease and of treatment
8. Special populations
9. Guideline/trial name if classic
10. Three exam traps

Coverage self-check

If you cannot answer any stem above from this page alone, re-read the matching section — the page is intended to be self-sufficient for final-prof and NEET-PG/INICET questions on Croup.

References21ShowHide

1. [1]Bjornson CL, Johnson DW Croup Lancet, 2008.PMID 18295000
2. [2]Cherry JD Clinical practice. Croup N Engl J Med, 2008.PMID 18216359
3. [3]Russell KF, Liang Y, O'Gorman K, Johnson DW, Klassen TP Glucocorticoids for croup Cochrane Database Syst Rev, 2011.PMID 21249651
4. [4]Bjornson CL, Klassen TP, Williamson J, et al A randomized trial of a single dose of oral dexamethasone for mild croup N Engl J Med, 2004.PMID 15385657
5. [5]Johnson DW, Jacobson S, Edney PC, et al. A comparison of nebulized budesonide, intramuscular dexamethasone, and placebo for moderately severe croup N Engl J Med, 1998.PMID 9709042
6. [6]Bjornson C, Russell K, Vandermeer B, et al. Nebulized epinephrine for croup in children Cochrane Database Syst Rev, 2013.PMID 24114291
7. [7]Westley CR, Cotton EK, Brooks JG Nebulized racemic epinephrine by IPPB for the treatment of croup: a double-blind study Am J Dis Child, 1978.PMID 347921
8. [8]Tibballs J, Watson T Symptoms and signs differentiating croup and epiglottitis J Paediatr Child Health, 2011.PMID 21091577
9. [9]Moore M, Little P WITHDRAWN: Humidified air inhalation for treating croup Cochrane Database Syst Rev, 2011.PMID 21678339
10. [10]Wall SR, Wat D, Spiller OB, et al The viral aetiology of croup and recurrent croup Arch Dis Child, 2009.PMID 18801765
11. [11]Kwon JH, Shin YH, Gil NS, et al. Analysis of the functionally-narrowest portion of the pediatric upper airway in sedated children Medicine (Baltimore), 2018.PMID 29979422
12. [12]Hopkins A, Lahiri T, Salerno R, Heath B Changing epidemiology of life-threatening upper airway infections: the reemergence of bacterial tracheitis Pediatrics, 2006.PMID 17015531
13. [13]Johnson DW Croup BMJ Clin Evid, 2014.PMID 25263284
14. [14]Klassen TP Croup. A current perspective Pediatr Clin North Am, 1999.PMID 10629679
15. [15]Petrocheilou A, Tanou K, Kalampouka E Viral croup: diagnosis and a treatment algorithm Pediatr Pulmonol, 2014.PMID 24596395
16. [16]Lee JH, Jung JY, Lee HJ Efficacy of low-dose nebulized epinephrine as treatment for croup: a randomized, placebo-controlled, double-blind trial Am J Emerg Med, 2019.PMID 30878411
17. [17]Parker CM, Cooper MN Prednisolone Versus Dexamethasone for Croup: a Randomized Controlled Trial Pediatrics, 2019.PMID 31416827
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19. [19]Lebecque P Childhood croup Arch Pediatr, 1999.PMID 10429820
20. [20]Asif A, Tayyab A, Qazi S Comparison between single-dose oral prednisolone and oral dexamethasone in the treatment of croup Ann Med Surg (Lond), 2023.PMID 37228932
21. [21]Geelhoed GC Budesonide offers no advantage when added to oral dexamethasone in the treatment of croup Pediatr Emerg Care, 2005.PMID 15942511