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6-minute read

What is croup?

Croup is an infection caused by a virus. It causes swelling of the windpipe (trachea), the airways to the lungs (the bronchi) and the vocal cords (voice box). This swelling makes the airway narrower, so it is harder to breathe.

Croup is often only a mild illness, but it can become serious quickly. It is very common in young children, mainly in children aged under 5 years.

What are the symptoms of croup?

Children may have symptoms of a cold before the onset of croup, including a runny nose, sore throat, fever and irritability. They then develop:

  • a harsh, barking cough
  • sometimes a hoarse voice
  • noisy breathing

The noisy breathing and cough are usually worse at night. They can also get worse if the child gets upset. In most children, the symptoms improve over a few days then disappear.

Children with croup may have noisy, squeaky breathing that is worse when breathing in. This is called stridor. It generally means there is some obstruction or narrowing of the windpipe. Occasionally, stridor is caused by a condition called epiglottitis (inflammation of the small cartilage ‘lid’ at the top of the airway) or anaphylaxis (severe allergic reaction). It might also be caused by an inhaled object (foreign body).

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

When should I call an ambulance?

You should call an ambulance by dialing triple zero (000) immediately if:

  • your child is struggling to breathe
  • your child looks very sick and becomes pale and drowsy
  • your child’s lips are blue in colour
  • your child starts to drool or can’t swallow

When should I see a doctor about croup?

Get medical help immediately if:

  • your child is less than 6 months old
  • your child has noisy breathing when at rest or is breathing more quickly than usual
  • the effort of breathing is tiring your child
  • your child is having trouble feeding, eating or drinking
  • your child’s nostrils flare as they breathe
  • your child becomes pale or blue after a coughing spell
  • you notice your child’s neck or breastbone being sucked in when they breathe in
  • your child becomes floppy
  • your child becomes restless, distressed, irritable and/or delirious
  • your child has a high temperature
  • the symptoms are getting worse
  • your child has mild croup that has lasted for more than 4 days
  • stridor (noisy, squeaky breathing)

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What causes croup?

Croup is caused by the same viruses that cause a cold or influenza (flu). These are spread through coughing, sneezing and touching infected objects.

Croup is more common in autumn and winter.

Children with underlying problems such as asthma and allergies are more likely to get croup

How is croup diagnosed?

A doctor can diagnose croup by talking to you about the symptoms and examining your child.

How is croup treated?

Most children with croup do not need treatment. You can manage the symptoms in the same way as for a cold. Encourage your child to drink plenty of fluids and keep them calm. They can have more trouble breathing if they are upset, frightened or stressed.

You can treat a fever with ibuprofen (for children over 3 months) or paracetamol. Do not give aspirin to babies or young children. The use of cough medicines is not recommended.

Steam therapy, including the use of vaporisors, is no longer recommended.

If your child's croup gets worse or you are worried, take your child to their doctor or the nearest emergency department for help.

Your doctor may prescribe medicines, such as an oral corticosteroid medicine, that can help reduce the inflammation and swelling. Antibiotics will not work because croup is caused by a virus. Antibiotics treat only bacterial infections.

A few children with croup need to go to hospital for observation, to ensure that they continue to be able to breathe without difficulty. While in hospital, your child might initially receive nebulised adrenaline (adrenaline given via a face mask) to relieve the spasm and swelling until the steroids work.

Can croup be prevented?

There is no way to prevent children from getting croup. However, you can try to limit the spread of the viruses that cause croup from your child to other people by:

  • washing your hands and your child’s hands regularly
  • encouraging your child to cough and sneeze into their elbow or into a tissue — throw the tissue away immediately
  • cleaning surfaces regularly to keep them free of germs
  • avoiding sharing unwashed cups, plates, cutlery and other kitchen utensils

If your child has croup, keep them away from childcare and school until 3 days after the illness started. This will prevent them from spreading the virus that caused the croup to others.

Because the influenza virus can sometime cause croup, flu immunisation (vaccination) might reduce the chance of your child developing croup.

What are the complications of croup?

There won’t be any permanent damage from having croup.

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Last reviewed: June 2021

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Croup & stridor: babies & children | Raising Children Network

If your child has a barking cough, hoarse voice and stridor (noisy breathing), they might have croup. Most children with croup don’t need special treatment.

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Croup is an infectious condition that causes inflammation of the voice box (larynx) and airways, resulting in breathing difficulties and a barking cough.

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Croup | Sydney Children's Hospitals Network

Croup is a common respiratory illness in young children which can cause narrowing of their airway

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Epiglottitis in babies, children & teens | Raising Children Network

Epiglottitis is a serious condition that affects children’s windpipes. If your well child suddenly develops breathing problems, get emergency medical help.

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