What causes croup?

Croup commonly follows a cold. Swelling around the larynx and trachea changes the child's cough to a harsh, barking sound and can make breathing noisy, particularly when breathing in. Symptoms are often worse at night because a small amount of swelling matters more in a child's narrow airway. Croup can affect children of different ages, but the airway response is especially noticeable in younger children.

A barking cough does not by itself show how severe the airway narrowing is. Watch the child's breathing effort, colour, alertness, and ability to drink.

Keep the child calm and hold them comfortably upright; crying can make noisy breathing worse. Offer frequent sips of fluid and check them regularly, including during the night. Avoid hot steam, which can burn, and do not give cough medicines unless a clinician or pharmacist recommends one for that child. A clinician may prescribe medicine to reduce airway swelling when symptoms require it.

Call emergency services if the child struggles to breathe, has noisy breathing while resting that is getting worse, pulls in at the ribs or neck, becomes unusually sleepy, cannot swallow saliva, or has blue, grey, or very pale lips. Seek urgent advice if the child is drinking poorly, has fewer wet nappies or trips to the toilet, or symptoms are progressing.

Ask how severe the airway swelling appears, which signs should prompt emergency help, and how to give any prescribed medicine. Tell the clinician when the barking cough began, whether noisy breathing occurs at rest, and how much the child is drinking.