Croup usually starts with an upper respiratory infection that travels to the larynx (the voice box). The hoarseness of the voice is due to the swelling of the vocal cords. It is usually caused by a virus, and lasts 5-6 days.

Your child might have one or more of the following symptoms when admitted to the hospital:

• Upper respiratory infection
• Stridor: a high pitched sound when breathing in, often is worse when the child is upset or crying, may worsen at night.
• Croupy cough: a hoarse, barky type of cough which may also worsen at night.
• Hoarseness
• Restlessness
• Irritability
• Low grade fever
• Difficulty in breathing: increased or rapid breaths