What is the incidence of croup in infants under 6 months old?

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Last updated: June 12, 2025View editorial policy

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From the Research

The incidence of croup in infants under 6 months old is relatively low, with this age group accounting for only about 5-15% of all croup cases. Croup (laryngotracheobronchitis) predominantly affects children between 6 months and 3 years of age, with peak incidence occurring around 24 months 1. The lower incidence in young infants is partly due to the larger relative diameter of their airways compared to older infants and toddlers, as well as maternal antibodies that provide some protection against viral infections in the first few months of life.

Key Points to Consider

  • When croup does occur in infants under 6 months, it requires careful evaluation as these young patients have smaller airways and less respiratory reserve, potentially making the condition more serious.
  • Treatment remains similar to older children, with humidified air, dexamethasone (0.15-0.6 mg/kg orally or intramuscularly), and nebulized epinephrine (2.25% racemic epinephrine or 1:1000 L-epinephrine) for moderate to severe cases, though hospitalization is more commonly recommended for this age group due to their vulnerability 1.
  • According to the most recent and highest quality study, croup affects about 3% of children per year, usually between the ages of 6 months and 3 years 1.

Additional Considerations

  • The use of heliox may be beneficial in the short term for children with moderate to severe croup treated with dexamethasone, but the evidence is limited and of low quality 2.
  • The effectiveness and safety of heliox are still uncertain, and adequately powered RCTs comparing heliox with standard treatments are needed to further assess its role in the treatment of children with moderate to severe croup 2.

References

Research

Croup: Diagnosis and Management.

American family physician, 2018

Research

Heliox for croup in children.

The Cochrane database of systematic reviews, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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