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Key points
- Croup is a viral infection that narrows the airway, making breathing harder.
- Children with croup may have a special type of noisy breathing called ‘stridor’ or a deep, barking cough that can start suddenly – often at night.
- The best way to care for a child with croup is to keep them calm and ensure they drink enough fluids. Doctors commonly prescribe steroids to reduce airway swelling.
- It is important to watch your child closely for signs that it is getting harder for them to breathe, such as sucking in under the ribs.
- If your child is struggling to breathe or making loud sounds when breathing, looks very pale and drowsy, has blue lips, or cannot swallow, call an ambulance (000) immediately.
What is croup?
Croup is an infection caused by a virus. It makes the voice box (larynx) and windpipe (trachea) swell, narrowing the airway and making breathing harder.
Children between six months and six years old are most likely to get croup. Some may need treatment with steroids to reduce airway swelling and make breathing easier.
Croup symptoms can worsen quickly, so it is important to watch your child closely. If your child is struggling to breathe or making loud sounds when
breathing, looks very pale and drowsy, has blue lips, or cannot swallow, call an ambulance (000) immediately.
Signs and symptoms of croup
Croup usually starts like a normal cold, with mild symptoms such as a fever, runny nose and cough. However, noisy breathing – known as 'stridor' – often develops suddenly during the evening or overnight because of the narrowing airway. It causes a squeaky
and high-pitched sound when your child breathes in.
Other common symptoms include:
- deep, barking cough like a seal
- hoarse or gravelly voice.
Depending on how narrow the airway gets, some children may struggle to breathe, and the skin between their ribs or under their neck may suck in with each breath. Like stridor (noisy breathing), this trouble breathing can start suddenly.
Croup symptoms are often worse on the second or third night of the illness.
The barking cough can last for up to a month.
Mild croup
If your child has mild croup, they may:
- have a cough and a husky voice, but they should be able to breathe easily and not make loud breathing noises.
Moderate croup
If your child has moderate croup, they may:
- have a cough and a husky voice
- find it hard to speak or breathe
- make a squeaky, high-pitched noise when they breathe in while upset, but not when they are calm. This is because their airway is partially blocked.
Severe croup
If your child has severe croup, they may:
- have a cough and a husky voice
- find it hard to speak and sound hoarse
- make a loud, high-pitched noise when they breathe in – even while resting
- work very hard to breathe, with the skin between their ribs or under their neck sucking in
- seem scared or anxious
- move around to find a comfortable position that makes breathing easier – often leaning forward.
How to care for croup
- Try to keep your child calm, as breathing is usually harder when they are upset.
- Encourage your child to get plenty of rest; their body needs energy to fight the virus.
- Ensure your child drinks enough fluids.
- If your child has trouble breathing, you should see a doctor. They may prescribe steroids to help reduce airway swelling. Antibiotics will not help croup because it is caused by a virus.
Croup can change quickly, so it is important to watch for signs that your child is getting worse. This often happens at night, so try to stay close so you can hear them.
If your child has stridor (noisy breathing) when they are resting, they will often need to be monitored closely in hospital.
If your child is struggling to breathe or making loud sounds when breathing, looks very pale and drowsy, has blue lips, or cannot swallow, call an ambulance (000) immediately.
When to get help
Call an ambulance (000) if:
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- your child is struggling to breathe, or they have stridor (noisy breathing).
- your child looks very sick, pale and drowsy.
- your child’s lips look blue.
- your child starts drooling or cannot swallow.
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Go to a hospital if:
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- your child has stridor (noisy breathing) when they are resting and calm.
- the skin between your child’s ribs or under their neck sucks in when they breathe while resting.
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See a doctor or health professional if:
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- your child has stridor (noisy breathing) when they are upset.
- your child's symptoms are getting worse.
- you are concerned they are dehydrated.
- you are worried for any other reason.
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Look after your child at home if:
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- it is easy for them to breathe while resting.
- they are drinking enough fluids.
- they are alert and can interact with you.
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Common questions about croup
Is croup contagious?
While croup itself is not contagious, the viruses that cause it are. These viruses spread mainly when an infected person coughs or sneezes. The best way to stop the spread of croup is to teach your child to practice good hygiene, such as washing
their hands regularly and covering their cough.
Which viruses cause croup?
Several different viruses can cause croup. The most common are parainfluenza and respiratory
syncytial virus (RSV).
Should I use steam to treat croup?
Steam is no longer recommended to treat croup. In the past, some doctors recommended mist or steam therapy for croup, including vaporisers. Scientific evidence now shows that these treatments do not help.
Can older children get croup?
Older children can get croup, but it is uncommon over the age of six.
How long does croup last?
Croup usually lasts two to four days/nights. Most symptoms last up to a week, but the cough can last up to a month.
My child's stridor has lasted longer than four days. What should I do?
If your child still has stridor – noisy, high-pitched breathing – after four days, you should see a doctor. This is unusual.
Can my child go to childcare or school when they have croup?
It is best to keep your child home from childcare or school while they have symptoms like a fever, runny nose or cough. When these symptoms get better, your child can go back to normal activities.
This podcast is also available in audio format below, and on Apple Podcasts and
Spotify.
Winter wellness season: Croup and your children
For more information
Developed by The Royal Children’s Hospital Emergency Department, with advice from the General Medicine department. We acknowledge the input of RCH consumers and carers.
Reviewed May 2025
Please always seek the most recent advice from a registered and practising clinician.