The characteristic signs of viral croup are:

• The infection often starts with a common cold or pharyngitis.
• A mild fever
• A typical ‘barking’ cough
• Inspiratory stridor is often, but not always, present. It is usually worse at night and then much better in the morning.
• Hoarseness of the voice is a less common sign in viral croup.

Viral croup typically presents at night with inspiratory stridor and a barking cough.