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Last updated: May 4, 2021

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Croup (acute laryngotracheobronchitis) is one of the most common infectious pediatric emergencies seen in winter. Commonly caused by the parainfluenza virus, croup is characterized by inflammation of the larynx and trachea. The clinical presentation varies depending on the severity of airway obstruction, but typically includes a barking cough, hoarse voice, and inspiratory stridor, all of which tend to occur at night. In moderate to severe cases, respiratory distress with subcostal and intercostal retractions occurs. Croup is primarily a clinical diagnosis, although a chest x-ray may be used to support diagnosis; laboratory tests and pulse oximetry help assess the severity of disease. In mild cases, treatment aims at alleviating symptoms and involves cold, moist air, calming the child, and corticosteroids. Moderate to severe cases require racemic epinephrine. Complications are rare: in cases of respiratory insufficiency, supplemental oxygen is necessary or even sedation and intubation. The prognosis of uncomplicated croup is good, with complete recovery occurring within seven days of onset.

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


Epidemiological data refers to the US, unless otherwise specified.


Prodromal phase

Laryngotracheal inflammation phase


Croup is primarily a clinical diagnosis, but imaging may be considered in mild cases of suspected croup. Other tests (e.g., pulse oximetry, blood gas analysis) help to assess the severity of disease. Identification of the viral pathogen is rarely necessary.

  • Based on clinical findings (see “Symptoms/clinical findings” above)
  • Pulse oximetry
  • X-ray of chest and neck: helps to verify subglottic narrowing, usually called steeple sign
  • In suspected cases of respiratory insufficiency: blood gas analysis (BGA)
  • If pneumonia or bacterial tracheitis is suspected: CBC
  • PCR: To identify the viral pathogen in tissue (e.g., nasopharyngeal washing)


Croup (subglottic laryngitis; laryngotracheitis)

Spasmodic croup

Epiglottitis (supraglottic laryngitis)

Laryngeal diphtheria

Foreign body (FB) aspiration
  • Accidental aspiration of a foreign body (e.g., nuts, raisins, seeds, pieces of toys)
  • Slow: 12–48 hours
  • Sudden onset during nighttime
  • 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
  • No toxic appearance
  • No toxic appearance
  • No fever
  • Toxic appearance, 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 findings
  • Most FB are radiolucent; focal overinflation of the distal lung may be visible
  • Approx. 16% of FB in larynx or trachea and 60% in the right lung
Response to inhalators
  • Mild croup: improvement after cool mist inhalation
  • Moderate to severe croup: improvement after epinephrine inhalation
  • Mild croup: improvement after cool mist inhalation
  • Moderate to severe croup: improvement after epinephrine inhalation
  • No improvement
  • No improvement
  • No improvement




The differential diagnoses listed here are not exhaustive.

Severity Treatment
Mild croup
  • Decrease infant's anxiety
  • Cool mist inhalation
  • Placing infant to sleep in an upright position
  • Breathing cool air at night (especially in the winter) helps to soothe symptoms
  • Dexamethasone
    • Reduces airway swelling within 6 hours
    • Long-lasting effect
    • Oral syrup, IV or IM injection
Moderate to severe croup

Intubation in severe croup is difficult due to subglottic narrowing → anesthesiologist required!



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

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


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