Last updated: September 12, 2023

Summarytoggle arrow icon

Viral croup (i.e., acute laryngotracheobronchitis) is an inflammation of the upper airway that occurs in young children. It is most often caused by the parainfluenza virus. This condition is characterized by a barking cough, hoarse voice, and inspiratory stridor, all of which often worsen at night. More severe symptoms are associated with higher degrees of airway obstruction and include signs of respiratory distress, which can rarely progress to respiratory failure. Croup is primarily a clinical diagnosis, and diagnostic studies are only performed for severe disease, diagnostic uncertainty, or recurrent episodes of croup. All patients with viral croup should receive glucocorticoids (preferably dexamethasone) and supportive treatment. Patients with moderate or severe croup should also be evaluated for admission and receive nebulized racemic epinephrine and supplemental oxygen. The prognosis of uncomplicated croup is good, and complete recovery typically occurs within seven days of onset.

Epidemiologytoggle arrow icon

  • Peak incidence: 6 months to 3 years
  • Most common in fall and winter


Epidemiological data refers to the US, unless otherwise specified.

Etiologytoggle arrow icon

Pathophysiologytoggle arrow icon

Clinical featurestoggle arrow icon

Do not examine the throat of a child with significant stridor because the resulting agitation may precipitate complete airway obstruction. [7]

Diagnosticstoggle arrow icon

General principles [3][8][9]

  • Croup is most commonly diagnosed based on the presence of characteristic clinical features of croup.
  • Diagnostic studies are not routinely required; do not delay treatment in unstable patients to obtain studies.
  • Indications for diagnostic studies include:

Do not delay treatment of stridor to perform diagnostic studies.


  • X-ray chest and neck (anteroposterior and lateral) [9]
    • May identify subglottic narrowing ; on anteroposterior view (steeple sign)
    • May show concurrent lower airway involvement [10]
  • CT chest and neck: usually performed for differential diagnoses or suspected underlying congenital abnormalities [3][11]
  • Laryngoscopy/bronchoscopy: may be performed for suspected foreign bodies or atypical croup [12]

The steeple sign is not specific to croup; it may also be present with bacterial tracheitis, epiglottitis, and noninfectious etiologies such as thermal injuries and neoplasms. [3]

Laboratory studies

Managementtoggle arrow icon

Approach [3][8][9]

Agitation can worsen symptoms and precipitate complete airway obstruction; keep children calm and defer distressing procedures (e.g., IV placement) until facilities are in place for immediate intubation if required. [15]

Nebulized racemic epinephrine rapidly relieves symptoms of respiratory distress. Dexamethasone provides longer symptom relief but takes up to 6 hours to reduce airway swelling. [3]

Humidified air, both in the hospital and as a home remedy (e.g., steam inhalation), has been used to treat croup, but there is no evidence that it is effective. [3][5][16]

Immediate stabilization [3]

Individuals with croup have difficult airways due to glottic and subglottic stenosis; if intubation is needed, notify anesthesia or ENT as early as possible. [3]

Evidence on the efficacy of helium-oxygen (heliox) mixtures in croup is mixed; routine use is not recommended. [18]

Croup severity assessment

  • Follow local or institutional protocols where available.
  • Croup scoring systems are susceptible to interobserver variability. [19]
  • The most commonly used score is the Westley croup score. [19]
Westley croup score [3][20]
Clinical features Score
Level of consciousness Normal 0
Disoriented 5
Cyanosis None 0
With agitation 4
At rest 5
Stridor None 0
With agitation 1
At rest 2
Air entry Normal 0
Decreased 1
Markedly decreased 2
Retractions None 0
Mild 1
Moderate 2
Severe 3


Over 80% of croup cases are mild. [21]


Suspect other causes of pediatric stridor if there are no symptoms of an upper respiratory infection and if symptoms do not respond to treatments for croup.


Admission criteria for croup [8][10]

Differential diagnosestoggle arrow icon


Overview of differential diagnoses of stridor [3][21][23]
Characteristics Croup (subglottic laryngitis; laryngotracheitis)

Spasmodic croup (atypical croup) [12]

Epiglottitis (supraglottic laryngitis)

Laryngeal diphtheria

Foreign body (FB) aspiration
  • Accidental aspiration of a foreign body (e.g., nuts, raisins, pieces of toys)
  • Slow: 12–48 hours
  • Sudden onset during nighttime with resolution of symptoms during the day
  • May recur on subsequent nights
  • Sudden: 4–12 hours
  • Initially slow, then sudden onset of symptoms after 4–5 days
  • Sudden
  • If the initial aspiration and choking episode is not witnessed, onset of symptoms (persistent or recurrent cough) days or weeks later

General condition

  • Well-appearing
  • Well-appearing
  • No fever
  • Acutely ill-appearing
  • Possible swollen neck
  • Barking
  • Barking
  • Absent
  • Barking
  • Choking
  • Hoarse
  • Hoarse
  • Muffled
  • Hoarse
  • Hoarseness or inability to speak indicate a laryngotracheal FB.
Difficulty swallowing/drooling
  • Absent
  • Absent
  • Present
  • Present
  • Depends on the location of the FB
X-ray neck and chest findings
  • Most FB are radiolucent and not visible on x-ray.
  • Indirect findings of FB include:
    • Chest: Focal hyperinflation of the distal lung on the affected side
    • Neck: widened prevertebral shadow and loss of cervical lordosis

Response to therapy for croup

  • No improvement
  • No improvement
  • No improvement

Additional differential diagnoses [3]

The differential diagnoses listed here are not exhaustive.

Complicationstoggle arrow icon

We list the most important complications. The selection is not exhaustive.

Prognosistoggle arrow icon

  • The prognosis in uncomplicated cases is good, with full recovery.
  • Parents should be aware that croup tends to recur.

Acute management checklist for crouptoggle arrow icon

Referencestoggle arrow icon

  1. Hospital JH. The Harriet Lane Handbook. Elsevier ; 2020
  2. Blaney SM, Giardino AP, Orange JS, et al. Rudolph's Pediatrics, 23rd Edition. McGraw-Hill Education / Medical ; 2018
  3. Smith DK, McDermott AJ, Sullivan JF. Croup: Diagnosis and Management. Am Fam Physician. 2018; 97 (9): p.575-580.
  4. American Academy of Pediatrics. Pediatric Education for Prehospital Professionals. Jones & Bartlett Publishers ; 2013
  5. Durand ML, Deschler DG. Infections of the Ears, Nose, Throat, and Sinuses. Springer ; 2018
  6. Rudolf M, Luder A, Jeavons K. Essential Paediatrics and Child Health. John Wiley & Sons ; 2020
  7. Bower J, McBride JT. Croup in Children (Acute Laryngotracheobronchitis). Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 2015: p.762-766.e1.doi: 10.1016/b978-1-4557-4801-3.00061-8 . | Open in Read by QxMD
  8. Moore M, Little P. Humidified air inhalation for treating croup. Cochrane Database Syst Rev. 2006.doi: 10.1002/14651858.cd002870.pub2 . | Open in Read by QxMD
  9. Ortiz-Alvarez O. Acute management of croup in the emergency department. Paediatr Child Health. 2017; 22 (3): p.166-169.doi: 10.1093/pch/pxx019 . | Open in Read by QxMD
  10. Walls R, Hockberger R, Gausche-Hill M. Rosen's Emergency Medicine. Elsevier Health Sciences ; 2018
  11. Moraa I, Sturman N, McGuire TM, van Driel ML. Heliox for croup in children. Cochrane Database Syst Rev. 2021; 2021 (8).doi: 10.1002/14651858.cd006822.pub6 . | Open in Read by QxMD
  12. Chan A, Langley J, LeBlanc J. Interobserver variability of croup scoring in clinical practice. Paediatr Child Health. 2001; 6 (6): p.347-351.doi: 10.1093/pch/6.6.347 . | Open in Read by QxMD
  13. Westley CR. Nebulized Racemic Epinephrine by IPPB for the Treatment of Croup. American Journal of Diseases of Children. 1978; 132 (5): p.484.doi: 10.1001/archpedi.1978.02120300044008 . | Open in Read by QxMD
  14. Cherry JD. Croup. N Engl J Med. 2008; 358 (4): p.384-391.doi: 10.1056/nejmcp072022 . | Open in Read by QxMD
  15. Parker CM, Cooper MN. Prednisolone Versus Dexamethasone for Croup: a Randomized Controlled Trial. Pediatrics. 2019; 144 (3).doi: 10.1542/peds.2018-3772 . | Open in Read by QxMD
  16. Lowen AC, Mubareka S, Steel J, Palese P. Influenza virus transmission is dependent on relative humidity and temperature. PLos Pathog. 2007; 3 (10): p.1470-6.doi: 10.1371/journal.ppat.0030151 . | Open in Read by QxMD
  17. Branche AR, Falsey AR. Parainfluenza Virus Infection. Semin Respir Crit Care Med. 2016; 37 (4): p.538-54.doi: 10.1055/s-0036-1584798 . | Open in Read by QxMD
  18. Brewster RC, Parsons C, Laird-Gion J, et al. COVID-19–Associated Croup in Children. Pediatrics. 2022; 149 (6).doi: 10.1542/peds.2022-056492 . | Open in Read by QxMD
  19. Bergelson J, Zaoutis T, Shah SS. Pediatric Infectious Diseases E-Book. Elsevier Health Sciences ; 2008
  20. Vezzetti R, Carlson J, Pennington D. Pediatric Imaging for the Emergency Provider E-Book. Elsevier Health Sciences ; 2021
  21. Cooper T, Kuruvilla G, Persad R, El-Hakim H. Atypical Croup. Otolaryngol Head Neck Surg. 2012; 147 (2): p.209-214.doi: 10.1177/0194599812447758 . | Open in Read by QxMD
  22. Greydanus DE, Patel DR, Reddy VN. Handbook of Clinical Pediatrics. World Scientific ; 2010
  23. Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2). McGraw-Hill Education / Medical ; 2018

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