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Croup

SNOMED: 71186008660 words•Updated 03/03/2026
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Exam Tips

  • Classify severity at rest: mild (bark only), moderate (stridor + recession), severe (stridor + marked recession + agitation/lethargy), impending failure (tiring, altered consciousness, cyanosis, may have quieter stridor).
  • In OSCEs, first action is to keep the child calm with parent and avoid upsetting manoeuvres; agitation can worsen obstruction.
  • Give single-dose dexamethasone early (oral 0.15 mg/kg) even in mild cases unless clear contraindication.
  • Do not examine the oropharynx if epiglottitis is suspected; urgent senior airway help is required.
  • Admission is indicated for moderate/severe croup, impending respiratory failure, or concerning context (very young infant, comorbidity, poor intake, safeguarding/logistical concerns).
  • Image recall: AP neck radiograph may show the steeple sign in croup, but this is not needed for diagnosis (see classic paediatric airway imaging figures in ENT/paediatric exam resources).

Definition

Croup (acute laryngotracheobronchitis) is a predominantly viral upper-airway illness of early childhood, classically affecting children aged 6 months to 3 years, and presenting with a sudden barking (seal-like) cough. It is caused by inflammation and oedema of the larynx, trachea, and especially the subglottic region, producing hoarseness, inspiratory stridor, and variable respiratory distress that are often worse at night and with agitation.

Pathophysiology

Most cases follow infection with parainfluenza virus (especially types 1 and 3), with mucosal inflammation of the larynx and trachea. Oedema is most clinically important in the subglottic space (the narrowest part of the young child’s upper airway), where a small reduction in radius causes a large rise in airflow resistance, increasing work of breathing and causing turbulent inspiratory flow (stridor). Agitation increases oxygen demand and dynamic airway narrowing, so distress can rapidly worsen clinical signs. This is why calm handling and early corticosteroid therapy are central to management.

Risk Factors

  • Age 6 months to 3 years (peak in second year of life)
  • Male sex (approximately 1.4:1 male: female)
  • Seasonal viral circulation (more admissions in late autumn; can occur year-round)
  • Possible weak association with previous intubation
  • Younger infants (<3 months) are higher risk for deterioration and lower threshold for admission

Clinical Features

Symptoms

  • Sudden onset barking (seal-like) cough
  • Hoarse voice
  • Noisy breathing/stridor (initially on exertion, then at rest if more severe)
  • Prodromal coryza, rhinorrhoea, non-barking cough, and low-grade fever for 12-72 hours
  • Symptoms worse at night
  • Poor oral intake may occur

Signs

  • Inspiratory stridor
  • Sternal/intercostal recession
  • Tachypnoea (RR >70/min suggests severe respiratory distress)
  • Agitation or lethargy in severe disease
  • Asynchronous chest-abdominal movement, pallor/cyanosis, reduced consciousness in impending respiratory failure
  • In tiring child, recession may lessen despite worsening airway failure

Investigations

Clinical diagnosis (history and examination):Typical barking cough with hoarseness +/- stridor; severity graded by stridor/recession/mental state
Pulse oximetry:May be normal in mild disease; low saturations indicate significant respiratory compromise
Investigations generally:Routine blood tests and imaging are usually not required and should not delay treatment
Neck/chest radiography (not routine):May show subglottic narrowing ("steeple sign") if performed, but diagnosis is clinical

Management

Lifestyle Modifications

  • Keep child calm and in position of comfort on carer’s lap; avoid unnecessary handling
  • Do not force throat examination if epiglottitis is possible (risk of sudden airway obstruction)
  • Encourage regular fluids; continue breastfeeding in infants
  • Safety-net carers: seek urgent help for persistent stridor at rest, increasing recession, agitation, drowsiness, cyanosis, drooling, or swallowing difficulty
  • Use antipyretic analgesia for fever/discomfort (paracetamol or ibuprofen if appropriate)

Pharmacological Treatment

Corticosteroid

  • Dexamethasone oral 0.15 mg/kg single dose immediately (mild croup and while awaiting transfer)
  • Dexamethasone intramuscular 0.6 mg/kg single dose if oral route not feasible
  • Budesonide nebulised 2 mg single dose if too unwell for oral medication

Give promptly to all severities unless contraindicated; reduces symptom burden and re-attendance. Single-dose treatment is usually well tolerated.

Nebulised adrenergic therapy (secondary care)

  • Adrenaline (epinephrine) nebulised 1 mg/mL (1:1000), 400 micrograms/kg (max 5 mg) per dose

Used for moderate/severe croup or impending respiratory failure in hospital due to short-lived effect and rebound risk; monitor continuously after dosing.

Supportive oxygen/analgesia

  • Controlled supplementary oxygen for severe croup or impending respiratory failure
  • Paracetamol oral 15 mg/kg every 4-6 hours (max 4 doses in 24 hours)
  • Ibuprofen oral 5-10 mg/kg every 6-8 hours (max 30 mg/kg/day)

Avoid ibuprofen in dehydration, renal impairment, or NSAID hypersensitivity/asthma sensitivity. Check age/weight-based BNF limits before prescribing.

Surgical / Interventional

  • Endotracheal intubation for impending respiratory failure/airway exhaustion (typically in critical care/anaesthetic setting)

Complications

  • Progressive upper-airway obstruction
  • Hypoxaemia and respiratory failure
  • Respiratory arrest (rare)
  • Dehydration from poor intake
  • Need for intubation (around 1-3% in impending respiratory failure)
  • Death is very rare (approximately <=1 in 30,000 cases)

Prognosis

Most children improve quickly, with symptoms settling within 48 hours (sometimes up to 1 week). Mild croup is often self-limiting, and corticosteroids shorten symptom duration and reduce re-presentation. With timely dexamethasone and, when needed, nebulised adrenaline plus supportive airway care, outcomes in severe croup are usually excellent.

Sources & References

🏥BMJ Best Practice(1)

💊BNF Drug References(1)

✅NICE Guidelines(1)

📖Textbook References(9)

  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 25)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1499)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1829)[context]
  • David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1499)[context]
  • Oxford Handbook of Clinical Diagnosis (Huw Llewelyn, Hock Aun Ang, Keir Lewis etc.) (Z-Library).pdf(pp. 299)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 411)[context]
  • [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 63)[context]
  • [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 706, 707)[context]
  • [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 706)[context]

Sources

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