What is it?

Croup is a viral infection which causes inflammation of the voice box (larynx) and windpipe (trachea). The inflammation means the lining swells and mucus production increases, which interferes with normal breathing.

Croup is often caused by a virus and begins with cold symptoms such as a runny nose, red eyes, and fever. Between two and six days later the child will develop a very distinctive cough, which sounds like a seal barking. The cough is caused by air passing through the swollen vocal cords.

Symptoms last for about five to seven days. Croup is often worse at night or when the child is upset and crying. Fever and a hoarse voice are also common symptoms.

Croup is most common in children six months to three years, but children younger and older can also get it. Children born prematurely due to their smaller airways and children with asthma are most at risk of developing croup.

How does it spread?

Croup is highly infectious and can be spread when droplets are coughed or sneezed into the air, or when droplets land on surfaces and toys which children then come into contact with.

Infectious period

Four to six days, until the fever settles.

Exclusion period

  • Tell parents that a child at the centre has croup.
  • Display information about croup on your notice board.
  • Make sure staff and children’s hands are washed often with soap and warm water and are thoroughly dried.
  • Clean all toys and surfaces with detergent, and then disinfect by wiping with or soaking in 1:10 dilute bleach. Disinfecting toys and general surfaces such as tables is a precaution for outbreaks, not a ‘normal’ procedure. When you don’t have an outbreak, frequent washing with detergent is okay.
  • Make sure there is adequate heating and air flow throughout the centre, particularly in sleep rooms.

Responsibilities of staff 

  • Keep your child home until the fever is gone and they are feeling well.
  • If your child experiences any of the following symptoms, they should be taken to the nearest emergency department, or call 111 immediately:
    • Stridor (high pitched whistling or crowing sound when breathing in).
    • Difficulty breathing, including rapid breathing.
    • Drooling or difficulty swallowing.
    • Cannot speak.
    • Extreme anxiety or frightened.
    • Blue or dusky-coloured lips.
    • Chest sinks in when trying to breathe in.


In most cases croup is a mild infection. Croup is a viral infection so does not respond to antibiotics and is usually well managed at home by simply keeping the child comfortable.


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Last updated 14 July 2022.