What is croup?

Croup (also called laryngotracheobronchitis) is caused by common viral infections such as parainfluenza and respiratory syncytial virus (RSV). It causes swelling and narrowing of the voice box (larynx) and airways. This can make it harder for your child to breathe.

There is no specific treatment for croup, but if breathing problems are severe, your child will need urgent medical attention.

Croup most often affects young children aged 6 months old to 5 years old.

What are the symptoms of croup?

Croup usually starts with cold symptoms such as fever, sore throat, red eyes and runny nose.

As croup progresses, your child may suddenly develop the following symptoms, often in the middle of the night:

• raspy or hoarse voice when crying or talking
• wheezing
• stridor — a harsh and high-pitched noise when your child breathes in and out
• a cough that has a distinctive ‘bark’ sound
• chest retractions, in severe cases — when the skin between your child’s ribs or under their neck may be pulled in when they breathe and cough
• floppiness, in severe cases — when your child is very weak (fatigued), not as alert as usual or it's hard to wake them

Symptoms usually last for about 2 to 5 days and peak during the second or third night of the illness.

Your child may have a cough that persists for several weeks even after they have otherwise recovered.

Some children suddenly develop croup in the middle of the night, without any other symptoms. Usually, these episodes settle after about an hour. This is called spasmodic croup.

Spasmodic croup is more common in children with asthma, or with a family history of allergy and asthma.

Read about how to tell if your child is sick.

Read about colds and flu in babies and children.

Read more about fevers in babies and children.

When should I call an ambulance or take my child to the emergency department?

Croup can get worse very quickly. It is important you seek medical help if your child shows signs they are struggling to breathe.

Do not drive your child to the hospital yourself if they are severely agitated, have blue-tinged skin, struggling to breathe or very drowsy. Call triple zero (000) and ask for an ambulance instead.

What should I do while waiting for the ambulance?

While you wait for an ambulance:

• try to keep yourself and your child calm
• do not forcibly change your child’s posture; they will have naturally chosen the best posture that helps them breathe
• be alert to any changes in your child’s symptoms

What should I do if my child does not need emergency healthcare?

If your child does not need emergency healthcare, but you are concerned, you should take them to their doctor.

Your child should see a doctor if:

• they are younger than 6 months old and have signs of croup
• their breastbone (sternum) or the skin between their ribs is drawn in when they breathe
• they have stridor (noisy breathing) even when they are resting
• they are very distressed or their symptoms are getting worse

Your child should also see a doctor if they have been unwell for more than 4 days with mild croup.

If your child has recovered from croup and their stridor returns, take them to see a doctor.

It’s always a good idea to see a doctor if you are worried about your child’s health.

What causes croup?

Croup can be caused by common viruses such as (but not limited to):

• parainfluenza virus
• respiratory syncytial virus (RSV)
• influenza virus
• covid-19

Not all children who catch these viruses develop croup. The viruses that cause croup can spread easily between people by coughing or sneezing.

How is croup diagnosed?

Your child’s doctor can diagnose croup by asking about your child’s symptoms and observing their breathing.

Parents sometimes suspect their child has croup even before they have been checked by their doctor, because their ‘barking’ cough is so distinctive.

How is croup treated?

Your child’s treatment will depend on how severe their croup is.

If your child has mild or moderate croup, they can usually be treated at home:

• Your doctor may prescribe a single dose of a steroid medicine.
• Give pain medicines, such as paracetamol, if your child has a fever or is irritable.
• Make sure your child is well hydrated.
• Keep your child calm — if your child becomes distressed, their symptoms may worsen.

Inhalations of humidified air or steam are not recommended. There is no evidence they are helpful, and they can cause burns.

If your child has severe croup, they should go to hospital immediately by ambulance.

They may receive medicines such as adrenaline through a nebuliser and oral steroid medicines. They will then usually be monitored for at least 4 hours in the hospital. If their stridor improves, they may be discharged home. If your child’s symptoms get worse or do not get better, they may be admitted to hospital.

Because croup is caused by a virus, antibiotics are not effective and are not recommended.

Read more about medicines for babies and children.

Read more about pain management in babies.

What are the complications of croup?

Croup doesn’t generally cause any long-term damage or complications.

In cases of severe croup, your child may have trouble breathing or dehydration that needs emergency medical care.

Can croup be prevented?

Croup can’t generally be prevented, but infection control measures can reduce the spread of viruses that cause croup.

Vaccines aren’t available for many of the viruses that cause croup.

There is a vaccination available against the influenza virus, one of the viruses that cause croup. For this reason, it’s a good idea to have your child immunised against influenza.

Learn more about immunisations and vaccinations for your child.

What you can do

Here are some tips to help prevent your child from catching and spreading viruses that can cause croup:

• If your child has croup, keep them home from school while they recover.
• Keep your child away from children who are unwell.
• Wash your child’s hands before they eat.
• When they are old enough, teach your child to cough and sneeze into their elbow or a tissue, and throw used tissues into a rubbish bin straightaway.
• Encourage your child not to touch their nose, eyes or mouth with their fingers.
• Be careful about your own hygiene and general health.
• Offer your child a healthy and nutritious diet that will help to support their immune system.

Resources and support

Talk to your doctor or child health nurse if you have questions about croup in babies and children.

You can call the healthdirect helpline on 1800 022 222. A registered nurse is available 24 hours a day, 7 days a week.

The Sydney Children’s Hospitals Network has a factsheet on croup.

Read about respiratory syncytial virus (RSV), one of the viruses that cause croup, on NSW Health's webpage.

Do you prefer to read in languages other than English?

Visit the Royal Children’s Hospital for resources translated into many community languages on:

• croup
• fever in children

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.