The term croup does not refer to a single illness, but rather a group of conditions involving inflammation of the upper airway that leads to a cough that sounds like a bark, particularly when a child is crying.

Most croup is caused by viruses, but similar symptoms may occasionally be caused by bacteria or an allergic reaction. The viruses most commonly involved are parainfluenza virus (accounting for most cases), adenovirus, respiratory syncytial virus, influenza, and measles.

Most children with viral croup are between the ages of 3 months and 5 years old. Croup is most likely to occur during the fall, winter, and early spring, and symptoms are most severe in kids younger than 3 years of age.

Most cases of croup due to viruses are mild and can be treated at home, though rarely it can be severe and even life-threatening. Some kids are more prone to developing croup, especially those who were born prematurely or with narrowed upper airways, and babies with a history of breathing problems like asthma.

The term spasmodic croup refers to a condition similar to viral croup, except that there are few accompanying symptoms of an infection. The cough frequently begins at night with a sudden onset and is often recurrent. The child usually has no fever with spasmodic croup. The symptoms are treated the same for either form of croup.

Signs and Symptoms

Croup is characterized by a loud cough that may sound like the barking of a seal and may be accompanied by fast or difficult breathing and sometimes a grunting noise or wheezing while breathing.

At first, a child may have cold symptoms like a stuffy or runny nose for a few days and may also have fever. As the upper airway (the lining of the windpipe and the voice box) becomes progressively inflamed and swollen, the child may become hoarse, with a harsh, barking cough.

If the upper airway becomes swollen to the point where it is partially blocked off, it becomes even more difficult for a child to breathe. This happens with severe croup. With severe croup, there may be a high-pitched or squeaking noise when breathing in (this is called stridor). A child will tend to breathe very fast, and the stomach or the skin between the ribs may seem to pull in during breathing since he or she is working hard to get air in to the lungs. The child may also appear pale or bluish around the mouth from not getting enough oxygen. These are signs that a child needs immediate medical attention.

Symptoms of croup often worsen at night and when the child is upset or crying. In addition to the effects on the upper airway, the infections that cause croup can result in inflammation further down the airway, including the bronchi (breathing tubes) and the lungs.


Croup tends to occur in outbreaks in the fall, winter, and early spring when the viruses that usually cause it peak. Many kids who come in contact with the viruses that cause croup will not get croup, but will instead have symptoms of a head cold. The viruses that cause croup can be passed when someone coughs or sneezes.


Doctors can usually diagnose croup by looking for the telltale barking cough and stridor, the squeaking sound on inhaling. They will also check for fever, cold symptoms (like a runny nose), or a recent viral illness, and ask questions to find out if the child has a prior history of croup or upper airway problems.

If croup is severe and slow to respond to treatment, a neck X-ray may also be taken to rule out any other reasons for the breathing difficulty, such as a foreign object lodged in the throat or epiglottitis (an inflammation of the epiglottis, the flap of tissue that covers the windpipe). Typical findings on an X-ray if a child has croup includes the top of the airway narrowing to a point, which doctors call a steeple sign.


Most, though not all, cases of viral croup are mild. Breathing in moist air seems to relieve many of the symptoms. Doctors will also sometimes treat with steroids, which helps with the airway swelling.

One way to humidify the air is with a cool-mist humidifier. Having your child breathe in the moist air through the mouth will sometimes break a croup attack. Or try running a hot shower to create a steam-filled bathroom where you can sit with your child for 10 minutes. While sitting in the bathroom (but outside of the shower), try cuddling and reading a bedtime story to help calm your child.

Sometimes, during cooler months, taking your child outside for a few minutes can help break the attack because the cool air can shrink the swollen tissues lining the airway. Parents can also try driving the child in the car with the windows down to bring in cool air.

If your child has croup, consider sleeping overnight in the same room to provide close observation. If your child is breathing quickly, working hard to breathe, has any stridor, seems less alert than usual, or seems to be worsening in any way, seek medical attention immediately.

Medical professionals will need to evaluate your child if the croup appears serious or if there's any suspicion of airway blockage or bacterial infection. Medications such as epinephrine or corticosteroids may be given to reduce swelling in the upper airways. Oxygen may also be given, and sometimes a child with croup will need to remain in the hospital overnight for observation and further treatment. As with most illnesses, rest and plenty of fluids are recommended.


The symptoms of croup generally peak 2 to 3 days after the symptoms of infection start. Croup resulting from viral infection usually lasts less 3 to 7 days.


The vast majority of kids recover from croup with no complications. Rarely, some will develop complications like pneumonia.

Children who were born prematurely or who have a history of breathing problems or lung disease (such as asthma) are more likely to develop severe symptoms of croup and may require hospitalization. Croup rarely causes any long-term complications.


Frequent hand washing and avoiding contact with people who have respiratory infections are the best ways to reduce the chance of spreading the viruses that cause croup.

When to Call the Doctor

Immediately call your doctor or seek medical attention if your child has any of the following symptoms:

  • difficulty breathing, including rapid breathing, belly sinking in while breathing
  • the skin between the ribs pulling in with each breath
  • stridor
  • pale or bluish color around the mouth
  • drooling or difficulty swallowing
  • greater inactivity than usual when ill or less alert than usual
  • high fever
  • very sick appearance
  • seems to be getting worse