Which virus causes croup?

Croup is identified from the sound and pattern of illness: a barking cough, hoarseness and sometimes a high-pitched noise when breathing in. A clinician can often recognise the pattern without testing for a specific virus. The [Croup](/conditions/croup/) page covers the condition itself.

Common cold viruses and other respiratory viruses can also irritate the upper airway. A fever may occur, but it does not identify the virus or predict the degree of airway narrowing. Read about [Common Cold](/conditions/common-cold/) and [Fever](/symptoms/fever/) for context.

Keep the child calm, hold them upright and offer fluids in small, frequent amounts. Check how they breathe while settled, because crying can make the noise louder. Follow the dosing directions for any fever medicine and avoid giving products intended for older children.

Steam can cause burns and is not a dependable way to relieve croup. Contact a clinician if the cough is worsening, drinking is reduced or you are uncertain about the breathing sound. A [Child Health Consultation](/treatments/consultations-and-assessment/child-health-consultation/) may be appropriate; urgent cases may be considered for [Nebuliser Treatment](/treatments/acute-and-urgent-care/nebuliser-treatment/).

Get emergency help if the child is struggling for each breath, the ribs or neck pull inward, the lips become blue or grey, or the child is difficult to wake. Drooling with difficulty swallowing or being unable to drink also requires urgent care.

Noisy breathing while resting should be assessed promptly, even if fever is mild. Tell the clinician whether the sound happens only with crying or also when calm. The [Cough](/symptoms/cough/) page can help you describe associated symptoms.

Ask whether testing would change care, whether the symptoms fit croup rather than a lower-airway illness, what to monitor during sleep, and which changes require emergency help.