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What is croup?

Croup is a common childhood illness that is caused by a viral infection. The virus causes swelling in the upper airways, including the larynx (the upper airway between the throat and the trachea) and th​e trachea (the windpipe or airway passage from the larynx to the lungs).

The swelling can cause changes in your child’s voice and make breathing difficult. This is especially likely in babies and younger children, because their airways are smaller.

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Croup is an infection that affects the upper part of the airway (larynx or voice box, and trachea or windpipe). This leads to swelling and narrowing of the airway.

Signs and Symptoms of c​rou​p

  • harsh "barking" cough
  • noisy breathing (stridor)
  • trouble breathing
  • hoarse voice
  • mild sore throat
  • runny or stuffy nose
  • fever

Stridor is a high-pitched noise that occurs when breathing through narrowed airways. In mild croup, your child may have stridor only when crying or coughing. If croup gets worse, your child may also have stridor when relaxed or sleeping, and may have trouble breathing.

Croup us​ually lasts for about 1 week

The viruses that cause croup usually last about 1 week. The barking cough and noisy breathing are usually worse during the first 2 or 3 days, and often worse at night.

Taking care of your child at home

For most children, croup is a mild illness that can be managed at home. Here are some ways to help your child feel better:

Cool m​ist

Cool, humid air may help reduce the swelling in the airways that is causing the noisy or difficult breathing. Placing your child near a cool mist vaporizer is ideal. If you do not have a cool mist vaporizer, even a simple humidifier in your child’s bedroom may be helpful. During the winter, you can open your child’s bedroom window to let in some cool air, or take your child outside for a short time to breathe in the cool night air.

Steamy bathr​oom

You can try running a hot shower with the bathroom door closed, so that the bathroom fills with steam. Sit with your child in the steam-filled bathroom for at least 10 minutes.

Fever and pain medi​cines

You can treat fever or sore throat with acetaminophen (Tylenol or Tempra) or ibuprofen (Motrin or Advil). DO NOT give your child ASA (acetylsalicylic acid or Aspirin).

Helping your child’s ​cough

Cough is a symptom of croup. There is nothing you can do to make the cough go away faster. The cough will get better as the virus runs its course.

However, the viruses that cause croup can also trigger wheezing in children with asthma and can sometimes cause a chest infection. Take your child to the doctor if your child’s cough seems severe, or if your child is having shortness of breath or is working hard to breathe.

Over-the-counter and prescription cold medicines are of no help for children and do not make the illness go away faster. Most cold and flu medicines are safe, but they can cause unwanted side effects, such as drowsiness, dizziness, trouble falling asleep or rapid heart rate. They can also cause rare serious side effects. Talk to your doctor before giving cold medicines to a young child, especially if your child is taking other medicines or has health problems. Never give your child cough and cold medicines if they are under 6 years of age.

Children with croup can suddenly start to have trouble breathing, and this can happen more than once. While your child has croup, you may wish to sleep in the same room. This will let you know about any problems during the night.

What can doct​ors do for croup?

Steroid m​edicine

Your doctor may prescribe a steroid medicine called dexamethasone​ taken by mouth. This medicine works to reduce the swelling in the airways. It takes a few hours for the steroid medicine to work fully, and the effect lasts for 24 to 36 hours. Usually only 1 or 2 doses are needed.


If your child is having severe problems breathing, your child may be given a medicine called epinephrine with a mask that sprays the medicine into your child’s airways. This medicine will reduce the swelling in your child’s airways very quickly. The effect lasts for about 4 hours. After 4 hours, the swelling may come back and your child may have problems breathing again. If epinephrine is needed, the doctor will want your child to stay in the Emergency Department for 4 to 6 hours or the doctor may keep your child in the hospital until their symptoms improve.

Croup can spread easily

The viruses that cause croup are contagious (spread easily from one person to another), especially during the first few days. Keep your child home from daycare or school until the fever is gone and the barky cough is going away. Keep your child away from young babies (under 2 months old) as much as you can.

Adults can become infected with the same virus that caused their child’s croup. However, adults and older children have larger airways, and the illness is usually mild and can seem more like a cold.

When to ​see a doctor

Call your child’s d​octor if:

  • the fever lasts more than 3 days
  • the cough lasts more than 1 week
  • your child is having noisy breathing
  • your child complains of an earache
  • you have other concerns or questions

Take your c​hild to the nearest Emergency Department or call 911 if:

  • the cool mist does not clear up the stridor in 15 minutes
  • your child has repeated episodes of stridor or trouble breathing
  • your child’s chest or stomach is pulling in while breathing
  • your child’s lips look blue or purple
  • your child starts drooling or spitting, has difficulty swallowing or refuses to drink
  • your child has neck pain or neck stiffness
  • your child seems lethargic (very sleepy) or irritable (very cranky)
  • your child stops drinking or urinating

Key p​oints

  • Croup is a common childhood illness that is caused by a viral infection.
  • For most children, croup is a mild illness that can be managed at home. There is no medicine that will make the virus go away faster, but there are ways to make your child more comfortable.
  • If croup is more severe, take your child to see a doctor.​

​​Reviewed by:
Trent Mizzi, BSc, MD, FRCPC