What is the first‑line treatment for a child with croup who has clinically significant airway narrowing (stridor at rest, marked retractions, or Westley croup score ≥ 8)?

Treatment for Croup with Significant Airway Narrowing

For a child with croup presenting with stridor at rest, marked retractions, or severe respiratory distress, immediately administer oral dexamethasone 0.15-0.6 mg/kg (maximum 10-12 mg) as a single dose PLUS nebulized epinephrine 0.5 mL/kg of 1:1000 solution (maximum 5 mL), followed by mandatory observation for at least 2 hours after the last epinephrine dose. 1, 2, 3

Immediate First-Line Treatment Algorithm

Step 1: Administer Corticosteroids Immediately

• Give oral dexamethasone 0.15-0.6 mg/kg as a single dose (maximum 10-12 mg) to ALL children with croup, regardless of severity. 1, 2, 3
• Oral dexamethasone is the gold standard and should be given immediately upon recognition of croup. 1
• If oral administration is not feasible, nebulized budesonide 2 mg is equally effective as an alternative. 2, 4
• The onset of action for dexamethasone is approximately 6 hours, so additional interventions may be needed for immediate symptom relief. 5

Step 2: Add Nebulized Epinephrine for Moderate-to-Severe Cases

• For children with stridor at rest, marked retractions, or significant respiratory distress, immediately add nebulized epinephrine 0.5 mL/kg of 1:1000 solution (maximum 5 mL). 1, 2, 3
• Nebulized epinephrine provides rapid but temporary relief, with effects lasting only 1-2 hours. 2, 3, 5
• The short duration of action necessitates close monitoring for rebound symptoms. 3, 5

Step 3: Provide Supportive Care

• Administer supplemental oxygen via nasal cannula, head box, or face mask to maintain oxygen saturation ≥94%. 2, 3
• Agitation may indicate hypoxemia rather than anxiety, requiring oxygen therapy. 3
• Keep the child comfortable with minimal handling to reduce metabolic and oxygen requirements. 2, 3
• Antipyretics can be used for comfort. 2, 3

Mandatory Observation Period

• Never discharge a patient within 2 hours of nebulized epinephrine administration due to the risk of rebound symptoms. 1, 2, 3
• Observe for at least 2 hours after the last dose of epinephrine to monitor for rebound airway obstruction. 1, 2, 3, 5
• If a second dose of epinephrine is required, restart the 2-hour observation clock after each dose. 3

Hospitalization Criteria

Consider hospital admission if the child meets ANY of the following criteria:

• Requires ≥3 doses of nebulized epinephrine (the "3 is the new 2" approach reduces unnecessary admissions by 37% without increasing revisits). 1, 2, 3
• Oxygen saturation <92%. 1, 2, 3
• Age <18 months. 1, 2, 3
• Respiratory rate >70 breaths/min. 1, 2, 3
• Persistent respiratory distress despite treatment. 1, 2
• Exhaustion, cyanosis, silent chest, or altered level of consciousness (life-threatening features). 3

Critical Pitfalls to Avoid

• Never use nebulized epinephrine in outpatient settings where immediate return is not feasible, as rebound symptoms can occur after the 1-2 hour effect wears off. 1, 3
• Never admit after only 1-2 doses of epinephrine when a third dose could be safely given in the emergency department with appropriate observation. 1, 2
• Never discharge before completing the mandatory 2-hour observation period after the last epinephrine dose. 1, 2, 3
• Never rely on cool mist therapy or humidified air as definitive treatment, as current evidence shows no benefit. 2, 3
• Never use antibiotics routinely, as croup is viral in etiology. 1, 2
• Never give over-the-counter cough medicines, antihistamines, or decongestants, as they have no proven benefit and can cause harm. 2, 3

Differential Diagnosis Considerations

Always consider alternative diagnoses in children who fail to respond to standard treatment or present atypically:

• Bacterial tracheitis (toxic appearance, high fever, purulent secretions). 2, 3
• Foreign body aspiration (sudden onset, unilateral findings, no prodrome). 2, 3
• Epiglottitis (toxic appearance, drooling, tripod positioning). 3, 6
• Retropharyngeal or peritonsillar abscess (neck stiffness, dysphagia). 3

Radiographic studies are generally unnecessary unless an alternative diagnosis is suspected. 2, 3

Discharge Criteria and Follow-Up

Children can be safely discharged home if ALL of the following are met:

• Resolution of stridor at rest. 2
• Minimal or no respiratory distress. 2
• Adequate oral intake. 2
• At least 2 hours have passed since the last epinephrine dose without rebound symptoms. 1, 2, 3
• Parents are able to recognize worsening symptoms and can return if needed. 2, 3

Instruct parents to return immediately if the child develops extreme fatigue, difficulty staying awake, inability to speak or cry normally, or worsening respiratory distress. 2, 3 If not improving after 48 hours, the child should be reviewed by a general practitioner. 2, 3