Croup often begins as a typical cold. If there's enough inflammation and coughing, a child will develop:

• Loud barking cough that's further aggravated by crying and coughing, as well as anxiety and agitation, setting up a cycle of worsening signs and symptoms
• Fever
• Hoarse voice
• Breathing that may be noisy or labored

Symptoms of croup are typically worse at night and usually last for three to five days.

Croup is usually caused by a viral infection, most often a parainfluenza virus.

Your child may contract a virus by breathing infected respiratory droplets coughed or sneezed into the air. Virus particles in these droplets may also survive on toys and other surfaces. If your child touches a contaminated surface and then touches his or her eyes, nose or mouth, an infection may follow.

Most at risk of getting croup are children between 6 months and 3 years of age. Because children have small airways, they are most susceptible to having more symptoms with croup.

Most cases of croup are mild. In a small percentage of children, the airway swells enough to interfere with breathing. Rarely, a secondary bacterial infection of the trachea can occur, resulting in trouble breathing and requiring emergency medical care.

Only a small number of children seen in the emergency room for croup require hospitalization.