Overview

Croup, medically called laryngotracheobronchitis, is an acute inflammation of the upper airway that most often affects young children. The swelling predominantly involves the larynx and subglottic trachea, which can narrow the airway and produce the characteristic noisy breathing. Typical features include a harsh, "barking" cough, inspiratory stridor and hoarseness. The illness ranges from a mild, self-limited condition to, rarely, severe airway obstruction requiring urgent care.

Symptoms and typical course

Symptoms commonly begin with nonspecific signs of an upper respiratory infection such as nasal congestion and low-grade fever. Within a day or two, the cough and voice changes develop and may worsen at night. Common findings include:

  • Barking cough — a seal-like cough that is often sudden and loud; see barking cough.
  • Stridor — a high-pitched sound on breathing in, especially when agitated or crying.
  • Hoarseness and a harsh or muffled voice.
  • Mild fever and signs of a viral cold.

Symptoms often peak in the first 48 hours and then improve over several days. Many children recover with simple measures at home, but some episodes—particularly in very young infants—can progress and require medical treatment.

Causes and pathophysiology

Croup is most commonly caused by viral infections of the respiratory tract; parainfluenza viruses are frequent culprits, though other respiratory viruses can be responsible. The infection causes mucosal swelling of the larynx and trachea; because the subglottic area is narrow in young children, modest swelling produces marked airflow limitation and turbulent airflow, which generates stridor and the barking cough.

Diagnosis and important distinctions

Diagnosis is primarily clinical and based on history and examination. Routine blood tests, throat swabs or x-rays are not required in typical cases. Physicians first consider and exclude other causes of noisy or obstructed breathing, including:

  • Foreign body aspiration — often sudden onset and asymmetric findings.
  • Epiglottitis — now less common in vaccinated populations but important to recognize because it can progress rapidly.
  • Bacterial tracheitis — a more severe, often post-viral bacterial infection that may present with high fever and very ill appearance.
  • Chronic conditions such as laryngomalacia — a congenital cause of noisy breathing that is usually present from birth.

Treatment and home care

Most children with croup improve with supportive measures and a single dose of steroid. Oral or intramuscular corticosteroids reduce airway swelling and decrease the need for further medical visits. In more severe cases with significant inspiratory stridor at rest or respiratory distress, nebulized epinephrine may be given in a monitored setting because it provides rapid, though temporary, relief of airway narrowing; see epinephrine.

Helpful home measures include keeping the child calm (crying worsens airway obstruction), offering comfort and fluids, and providing cool, moist air. Steam or a brief exposure to cool night air can ease breathing for some children. After receiving nebulized epinephrine, children are observed for recurrence of symptoms because the effect can wear off.

When to seek urgent care

  1. Stridor at rest, rapid breathing, or obvious difficulty breathing.
  2. Drooling, inability to swallow, or a very high fever.
  3. Cyanosis (blue lips or face), decreased responsiveness, or extreme lethargy.

These signs require immediate medical evaluation. Hospitalization is uncommon but may be necessary for severe or persistent respiratory compromise, or when close observation is needed in infants.

Notable facts and prevention

Croup is common in young children, with many children experiencing at least one episode in early childhood; incidence peaks between about 6 months and 5–6 years of age. It also tends to be seasonal, occurring more often in the autumn and winter months when respiratory viruses circulate. General infection-control measures such as handwashing and keeping sick children at home help reduce spread. Vaccination against other respiratory pathogens has reduced some serious alternate diagnoses (for example, epiglottitis from Haemophilus influenzae type b).

Overall, croup is usually manageable with timely supportive care and appropriate medical treatment when indicated. Awareness of warning signs and differentiation from other, potentially more dangerous airway conditions are key to safe management.