Croup is caused by an acute viral infection of the upper respiratory tract. It is also called laryngotracheobronchitis since it affects the larynx, trachea, and bronchi.
This infection ends up in inflammation, increased secretion production, and swelling of the higher airways.
Although croup usually resolves on its own, some children with croup will require admission to the hospital. Croup continues to be one of the most common causes of respiratory distress in young children.