Overview of Croup

Croup is an inflammatory condition that is more common in younger children. Croup affects the upper respiratory tract and causes swelling and increased mucus production. It often occurs following an acute respiratory infection, such as a cold, and results in a distinctive barking cough and abnormal, high-pitched breathing sounds.

The upper respiratory tract includes the following:

  • Larynx (voice box with vocal chords)
  • Pharynx (top of throat where the openings of the mouth and nose meet)
  • Epiglottis (flap of tissue in the throat that prevents food and liquids from entering the windpipe)
  • Trachea (windpipe that leads to bronchi)
  • Bronchi (tubes that branch off the trachea and lead into the lungs)

The barking cough of croup is due to swelling and inflammation around the vocal chords and windpipe (i.e., the larynx and trachea). Although most children with croup improve within a few days, hospitalization may be necessary in severe cases.

Types of Croup

There are different types of croup and different ways to categorize the condition. Croup can be differentiated by the cause (e.g., virus, bacteria) or by the specific symptoms that accompany the cough.

Croup caused by a virus is called viral croup. Viral croup is the most common type. It is caused by viruses, such as adenoviruses (cold viruses) and influenza (flu) viruses, and usually is associated with other symptoms (e.g., fever, runny nose). Laryngotracheitis is a type of viral croup that involves swelling of the larynx and trachea.

Spasmodic croup is not associated with other symptoms. This type often develops suddenly and recurs. Spasmodic croup sometimes can be caused by an allergen (e.g., pollen) or a bee sting.

Bacterial croup is caused by a bacterial infection. This type is much less common than viral croup.

Incidence and Prevalence of Croup

Each year about 5% of young children develop croup. The condition occurs more often in boys than in girls. Some children may be prone to developing croup and get the condition more than once.

Croup is typically seen among infants, toddlers, and young children. It is most common in children between the ages of 3 months and 6 years. Breathing passages are larger in older children and adolescents, so upper respiratory tract swelling and inflammation usually do not result in croup symptoms. Although rare, it is possible for children over 6 years old to get croup.

Croup can occur at any time of year, but it is most common during cold and flu season—generally late fall and winter.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 27 Aug 2008

Last Modified: 10 Sep 2015