Croup is an infection of the voice box (larynx) and windpipe (trachea). These are the upper and lower parts of the breathing tube that connect the mouth to the top of the lungs. The usual cause of croup is a viral infection.

Croup often causes mild symptoms that get better quickly. Sometimes the symptoms can be more serious and include problems with breathing. It's really important that your child be seen by a doctor if you think they have croup. Children with croup who have difficulty with breathing need immediate admission to hospital.

Lungs and airways croup

How common is croup?

Croup is common in young children, especially between the ages of 6 months and 3 years. Some children have two or more bouts of croup in their childhood. The viral infection can pass from person to person, especially if there is close contact. Croup often occurs in outbreaks or epidemics in the winter.

Croup is uncommon after the age of 6 years. Older children can get the same viruses but the breathing tube becomes wider and stronger so the virus doesn't usually cause croup. However, teenagers and, very rarely, adults can get croup.

When should you seek medical help?

Always consult a doctor or nurse if you have any concerns about your child. Most children with croup have mild symptoms and soon get better. However, a small number of children with croup need to be admitted to hospital. In particular, see a doctor quickly if:

  • Breathing symptoms get worse. (Breathing is often noisy with mild croup but it's difficulty in breathing that is worrying.) Signs that breathing is getting worse include: rapid breathing; needing more effort to breathe; you may see the chest or neck muscles being pulled in with each breath.
  • The child becomes restless or agitated.
  • The child looks unusually pale.
  • A high temperature (fever) lasts longer than five days.

And call for an emergency ambulance if the child is:

  • Blue (cyanosed).
  • Unusually sleepy.
  • Struggling to breathe.
  • Drooling and unable to swallow.

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Dr Colin Tidy
Peer Reviewer:
Prof Cathy Jackson
Document ID:
4429 (v44)
Last Checked:
16 February 2015
Next Review:
15 February 2018

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.