What is Croup?

What is Croup?

Croup (laryngotracheobronchitis) is a respiratory infection that affects young children. Viral infections are the most common cause of the condition. Croup causes swelling of your child’s voice box (larynx) and windpipe (trachea). This swelling causes the airway below their vocal cords to narrow, which makes their breathing noisy and difficult.

Croup in babies is most common, along with children younger than 3 years old. As children get older, croup isn’t seen as often. This is because their windpipes get larger and swelling is less likely to get in the way of their breathing.

Croup causes a distinctive cough that may sound similar to the call of a seal. The condition is usually mild but symptoms can become severe and life-threatening.

RSV vs. croup — what’s the difference?

RSV (respiratory syncytial virus) and croup are both respiratory illnesses that can affect babies and young children. RSV is a viral infection that can affect both children and adults. It causes coughing, sneezing and other cold-like symptoms.

While RSV is its own illness, the respiratory syncytial virus is also one of the viruses that can lead to croup.

Whooping cough vs. croup — what’s the difference?

Whooping cough (pertussis) and croup are both respiratory infections that can affect babies and children. Both conditions cause a distinctive cough, although the sound of whooping cough is a more high-pitched gasping or “whooping” noise.

Whooping cough is a bacterial infection whereas a viral infection usually causes croup. Therefore, no vaccines can prevent croup and antibiotics can’t treat it. (Antibiotics can’t kill viruses.) There’s a vaccine to prevent whooping cough, but it doesn’t go away quickly on its own as croup usually does.

How common is croup?

Croup affects about 3% of U.S. children every year. The condition accounts for 7% of all hospitalizations in children younger than 5 years old. It’s more common in boys and children assigned male at birth (AMAB) than girls and children assigned female at birth (AFAB). Healthcare providers define about 85% of croup cases as mild. They consider less than 1% of cases severe.

Symptoms and Causes

What does croup sound like?

The croup cough sounds like a harsh “barking” sound. This is the most common symptom of croup. Your child may also have stridor, which is a raspy, vibrating sound that occurs when your child is breathing in.

What are the other symptoms of croup?

Croup is typically mild and lasts less than one week, but symptoms can get more severe. Symptoms normally start slowly and may begin with a runny or stuffy nose. Over the next 12 to 48 hours, symptoms can worsen and the barking cough may start. Symptoms are usually worse at night.

Other mild croup symptoms include:

  • Hoarseness.
  • Fever.
  • Rash.
  • Eye redness (conjunctivitis).
  • Swollen lymph nodes.

Symptoms of moderate to severe croup may include:

  • Difficulty breathing.
  • Restlessness or nervousness.
  • Retractions (sucking in the skin around your child’s ribs and the top of their breastbone).
  • Cyanosis (blue-tinged skin).

What causes croup?

The most common cause of croup is a viral infection. Croup viruses include parainfluenza, influenza, respiratory syncytial virus (RSV), measles and adenovirus. Viral croup causes your child’s upper airways to swell, making it difficult for them to breathe. However, these viruses are common and most children with viral infections don’t develop croup. Rarely, bacteria can complicate the viral infection and make it more difficult to breathe.

Is croup contagious?

Yes, croup is highly contagious because the viruses that lead to the condition are easily spreadable.

How do you get croup?

The viruses that cause croup spread easily through the air. When someone with a viral or bacterial infection that can cause croup sneezes or coughs, they send respiratory droplets containing croup-causing germs into the air. When your child breathes in these droplets, they can catch an illness that’ll cause croup. Your child can also get croup by touching objects contaminated by germs that can cause croup.

How long is croup contagious?

Your child is contagious for three days after their symptoms first appeared or until their fever is gone. You should keep your child home from school until 24 hours have passed without a fever and without using fever-reducing medication.

What are the complications of croup?

Most cases of croup are mild and you can treat them at home. Complications of croup are rare. Less than 5% of children with croup need in-hospital care. Your child’s condition may lead to hospitalization if they:

  • Need oxygen therapy to keep their oxygen levels within a safe range.
  • Have severe dehydration that requires IV (intravenous, or through your vein) fluids.
  • Need multiple doses of inhaled breathing treatments to provide relief.
  • Have severe symptoms despite initial treatment.

Diagnosis and Tests

How can I tell if my child has croup?

You can usually tell if your child has croup based on their signs and symptoms. The most common symptoms are a barking cough and stridor. This condition is especially widespread in the fall and winter months. If your child’s condition is severe, a healthcare provider may order X-rays and laboratory tests, but this is rare.

Management and Treatment

How is croup treated?

Croup treatment depends on the severity of your child’s condition and the risk of it rapidly worsening. If your child has a history of respiratory problems or was born prematurely, that may also affect the treatment approach.

Mild croup

You can usually treat mild croup at home. Home treatment includes using a cool mist humidifier to help soothe dry and irritated airways. You can also sit with your child in a bathroom filled with steam generated from hot water running in the shower. (Don’t sit in the shower or let your child near the hot water.) If your child’s condition doesn’t improve with mist treatment, you should contact their healthcare provider.

Other croup home remedies include:

  • Letting your child breathe cool air at night by opening a door or window.
  • Treating your child’s fever with an over-the-counter (OTC) medication such as acetaminophen (Tylenol®) or ibuprofen (Advil®).
  • Treating your child’s cough with warm, clear fluids to help loosen the mucus on their vocal cords.
  • Avoiding smoking in your home, as smoke can worsen your child’s cough.
  • Keeping your child’s head elevated with an extra pillow. (Don’t use pillows with infants younger than 12 months old.)

You may wish to sleep in the same room as your child so you’re there if they start to have trouble breathing.

Moderate to severe croup

For moderate to severe croup, you should take your child to the nearest urgent care center or emergency room (ER). Severe croup can be life-threatening, and you shouldn’t delay taking your child in. Treatment for moderate to severe croup will vary based on your child’s symptoms. Croup treatments may include:

  • Humidified air or oxygen.
  • IV fluids for dehydration.
  • Monitoring of vital signs, including oxygen levels, breathing and heart rate.
  • Croup medication, including steroids (glucocorticoids) and nebulized breathing treatments (epinephrine).
  • Placement of a breathing tube (mechanical ventilation). This is rare.

Specific croup medication

If you take your child to their provider’s office or the emergency room, their provider will give them a glucocorticoid and a nebulized breathing treatment (epinephrine).


Glucocorticoids are a type of steroid that decreases the swelling of your child’s voice box (larynx), typically within six hours of the first dose. For a child with mild croup, glucocorticoids may reduce the need for a repeat visit to their provider’s office or the emergency room.

The glucocorticoids healthcare providers use most often are dexamethasone and prednisolone. Your child will usually only need one dose taken by mouth (orally). If your child is vomiting or can’t keep the medicine down, their provider can also give dexamethasone intravenously (IV) or through an intramuscular (IM) injection.

Nebulized breathing treatment (epinephrine)

Your child will receive epinephrine as an inhaled mist (nebulizer). This also reduces the swelling in your child’s airways and usually starts working within 10 minutes. Epinephrine works for two hours or less, and your child may receive this treatment every 15 to 20 minutes for severe symptoms.

Complications/side effects of the treatment

Serious side effects of epinephrine are rare. However, side effects could include a rapid heartbeat (tachycardia). A healthcare provider will monitor your child for three to four hours after their last dose to ensure symptoms of airway blockage don’t return.

How soon after treatment will my child feel better?

Glucocorticoids usually start working within six hours of the first dose. Epinephrine typically begins working faster than glucocorticoids.


How can the spread of croup be prevented?

Croup can spread by physical contact or through the air. To help prevent its spread:

  • Wash and dry your hands thoroughly after caring for your child.
  • Wash toys between each use.
  • Encourage your child to cover their mouth and nose when coughing and sneezing.
  • Keep your child home from school or daycare when they’re ill or if outbreaks occur.
  • Throw used tissues away.

Outlook / Prognosis

When should I worry about croup?

Croup can be mild, moderate or severe, depending on how difficult it is for your child to pull air into their lungs. The size (diameter) of their windpipe and the amount of narrowing due to the swelling determine the severity of your child’s condition. In addition, your child’s condition may become more severe if they become upset.

Mild croup

A child with mild croup may have a barking cough and stridor. Symptoms can worsen throughout your child’s illness, especially during the evening hours. So it’s important to keep an eye on their breathing, but you can usually treat their condition at home.

Moderate croup

A child with moderate croup may have stridor along with retractions (sucking in the skin around their ribs and the top of their breastbone). They may also be slightly agitated or disoriented and may have moderate trouble breathing. You should take your child to see a healthcare provider for treatment.

Severe croup

A child with severe croup has stridor and retractions. They may also be agitated, anxious or fatigued. Cyanosis (blue-tinged skin) is common. Severe croup is a life-threatening condition. Take your child to the emergency room immediately.

How long does croup last?

Symptoms of croup usually clear up in most children within two days. However, symptoms can persist for up to one week.

When can my child go back to school?

Croup is very contagious. Your child should stay home from school until after their fever is gone.

Living With

When should I take my child to see their healthcare provider?

You should call your child’s healthcare provider if:

  • Your child has a fever that lasts for more than three days.
  • Your child has symptoms of mild croup that last for more than one week.
  • You have questions or are concerned about your child’s condition.

When should I go to the ER?

If your child develops symptoms of severe or worsening croup, seek immediate medical attention. These symptoms include:

  • Difficulty breathing.
  • Blue-tinged skin (cyanosis).
  • Severe coughing spells.
  • Drooling or difficulty swallowing.
  • Inability to cry or speak due to trouble taking a breath.
  • A noisy, high-pitched whistling sound while breathing.
  • Sucking in the skin around your child’s ribs and the top of their breastbone (retractions).

Additional Common Questions

Why does my child keep getting croup?

If your child keeps getting croup, it may be a sign they have a narrowing in their airway and that they’re at a higher likelihood to be affected by the infection. Your child may have been born with the narrowing or it may have developed after birth. If croup returns (recurs) repeatedly, your child’s provider may refer them to a specialist such as an otolaryngologist (ear, nose and throat doctor) or a pulmonologist (breathing and lung disease doctor).

Can adults get croup?

Adults can get croup, but it’s rare. The reason babies and young children get croup is because their windpipes (tracheas) are narrower and not fully developed. As children get older, their windpipes get larger and fully develop, so any swelling is less likely to affect breathing. Adults have larger airways, so croup doesn’t typically affect them. When adults do get croup, their symptoms are usually worse and they may need more aggressive treatment.


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