Definition: Respiratory illness defined by inspiratory stridor, cough and hoarseness in the setting of viral illness.


  • Croup may be caused by a number of viruses. 
  • Common Causes: parainfluenza virus, influenza virus, adenovirus and respiratory syncytial virus.
  • Rare Causes: human metapneumovirus, measles, varicella, human coronavirus or HSV-1.


  • Age 6 months to 36 months most common
    • Can be seen in 3 month up to preschool age, uncommon >6years
  • Peak mid fall to early winter
  • Peak time to visit ED 10pm-4am


  • Intubation may be required for severe respiratory distress
  • Bacterial tracheitis can cause rapid deterioration
    • Also called bacterial laryngotracheobronchitis
    • Bacterial super-infection that can mimic viral croup
    • Common pathogens: staph aureus, strep pneumo, group A strep, Moraxella
    • Rarely: Pseudomonas, Haemophilus parainfluenzae, Klebsiella, E.Coli
  • Pneumonia is a rare complication

Differential Diagnosis

  • Life-threatening mimics of croup
    • Infectious: Acute Epiglottitis and Bacterial Tracheitis
    • Mechanical: Inhaled Foreign body and Allergic reaction/anaphylaxis
  • Other less emergent cause of stridor and/or barky cough:
    • Infectious: Peritonsillar/retropharyngeal abscess, Ludwig’s angina, laryngeal diphtheria and cervical adenitis
    • Mechanical: Upper airway injury, Congenital upper airway anomalies, neck/c-spine trauma, smoke inhalation, neck masses, laryngomalacia


  • 1-3 days of nonspecific upper airway obstruction
  • Barking, seal-like cough
  • Low grade fever
  • Nighttime symptoms

Physical Exam

  • Stridor at rest or only with agitation/coughing
    • Biphasic stridor indicates high grade obstruction
  • Respiratory distress
    • Tachypnea
    • Retractions/flaring
  • Assess the patients:
    • Air entry
    • Skin color
    • Consciousness
    • Hoarse voice

Westley Croup Score

When agitated 1
At rest 2
Mild 1
Moderate 2
Severe 3
AIR ENTRY Normal 0
Decreased 1
Markedly decreased 3
With agitated 4
At rest 5
Disoriented 5
TOTAL SCORE: Mild 1-2, Moderate 3-8 Severe >8

The Westley croup score is mostly used for research purposes but may help guide clinical management and disposition if used at presentation


  • Supportive maneuvers include avoidance of agitating the child most importantly. 
  • Humidified air has limited evidence for efficacy (Moore 2006)
  • Epinephrine
    • Nebulized Epinephrine causes alpha adrenergic vasoconstriction to reduce airway edema and improves symptoms within 30 minutes (Bjornson 2013)
    • Racemic Epinephrine and L Epinephrine are equally efficacious (Waisman 1992).
      • Can be repeated every 20-30 minutes as needed
      • Wears off in 2-4 hours
  • Corticosteroids: Corticosteroids decrease airway inflammation and edema
    • Reduces unscheduled return visits in patients with mild croup (Bjornson 2004)
    • Dexamethasone can be given intramuscularly and orally (0.6mg/kg max 8-20mg)
    • Alternatively, Prednisolone or Prednisone can be administered orally for 3 days (1-2mg/kg/day max 60mg) (Sparrow 2006)
  • HeliOx: Heliox is a combination of helium and oxygen
    • 2 concentrations available, 70% helium 30% oxygen and 80% helium and 20% oxygen. T
    • Lower density of the mixture results in decreased airway turbulence
    • Heliox cannot be used in in patients requiring more than 30% oxygen
    • Heliox may be considered in the patient with severe croup to possibly forestall intubation


  • Patients without stridor at rest or respiratory distress can generally be discharged from emergency department.
  • Patients treated with epinephrine should be observed for 2-4 hours for reemergence of symptoms as the medication wears off.
  • The patient may return to pretreatment symptoms but rarely worsen.   
  • Most patients who receive 2 or more doses of epinephrine in the ED do not have any significant interventions in the inpatient setting (Rudinsky 2015)
  • Some patients with significant airway edema will require intubation.   These patients will need ICU level care. 
  • In the child with prolonged symptoms who is highly febrile with deteriorating respiratory status the diagnosis of bacterial tracheitis should be considered.

Take Home Points

  • Croup usually has a benign course, but can lead to life threatening respiratory compromise
  • High fever, toxic appearance and poor response to therapy suggests bacterial tracheitis or other diagnosis
  • Children with persistent stridor after treatment with racemic epinephrine and dexamethasone require admission

Read More

Don’t Forget the Bubbles:  “Croup” Henry Goldstein

PEM Guides Michael Mojica “Croup – Dennis Heon”

“Clinical Practice. Croup” JD Cherry New England Journal of Medicine


Bjornson CL et al. A randomized trial of a single dose of oral dexamethasone for mild croup. N Engl J Med. 2004 Sep 23;351(13):1306-13. PMID: 15385657

Bjornson C et al. Nebulized epinephrine for croup in children. Cochrane Database Syst Rev. 2013 Oct 10;(10). PMID: 24114291

Cherry, JD Clinical Practice. Croup. N Engl J Med. 2008 Jan 24;358(4):384-91 PMID: 18216359

Moore M, Little P. Humidified air inhalation for treating croup. Cochrane Database Syst Rev. 2006 Jul 19;(3). PMID: 16855994

Rudinsky SL et al. Inpatient Treatment after Multi-Dose Racemic Epinephrine for Croup in the Emergency Department. J Emerg Med. 2015 Oct;49(4):408-14. PMID: 26242923

Sparrow A, Geelhoed G. Prednisolone versus Dexamethasone in croup: a randomized equivalence trial. Arch Dis Child. 2006 Jul;91(7):590-3. PMID: 16624882

Toward Optimized Practice (TOP) Working Group for Croup. 2008 January. Diagnosis and management of croup. Edmonton, AB: Toward Optimized Practice. Available from:

Waisman Y et al. Prospective randomized double-blind study comparing L-epinephrine and racemic epinephrine aerosols in the treatment of laryngotracheitis (croup). Pediatrics. 1992:89(2):302-6. PMID: 1734400