Croup is one of the most common respiratory illnesses in children. It is an inflammation of the larynx and the trachea. When a child has croup, that portion of the airway just below the vocal cords narrows and becomes swollen, making breathing both noisy and labored.


Croup is a broad term describing a group of illnesses that affect the larynx, trachea, and bronchi. The key symptom is a harsh, barking cough . One of the most common respiratory illnesses in children, croup is frequently noted in infants and children and can have a variety of causes. Before the days of antibiotics and immunizations, croup was a dreaded and often deadly disease usually caused by the diphtheria bacteria. Though in the early 2000s cases of croup are normally mild, it can still be dangerous. Croup affects the vocal cords and the area just below, the voice box, or larynx, and the windpipe, or trachea. The lower breathing passages (bronchi) may also be affected. Swelling of these areas causes the airway to narrow, which makes breathing difficult. It is also sometimes called laryngotracheitis, a medical term describing the inflammation of the trachea and larynx.

The characteristic symptoms of croup can be better understood by knowing the anatomic makeup of a child's larynx. Small children typically have quite a narrow larynx, so even a slight decrease in the airway's radius may lead to a large decrease in the air flow, leading to the symptoms of croup.

There are two primary types of croup: viral and spasmodic. Viral croup is caused by a viral infection in the trachea and larynx. It often starts with a cold that over time develops into a barking cough. When the child's airway becomes increasingly swollen and more mucus is secreted, it becomes more challenging to breathe. Breathing gets increasingly noisy, and a condition known as stridor may occur. (Stridor is a sign of respiratory obstruction that presents as a high-pitched, coarse, musical sound that occurs during breathing.) Children with viral croup usually have a low-grade temperature, but a few may have fevers up to 104°F (40°C). As breathing requires more effort, the child may stop eating and drinking. The child may also become too fatigued to even cough. If the airway continues to swell, it may approach a point at which the child can no longer breathe. Stridor is fairly common with a mild case of croup, especially if the child is active or crying. However, if a child has stridor at rest, the child may have severe croup. Symptoms are usually worse at night. The symptoms peak between 24 and 48 hours and usually resolve within one week.

Spasmodic croup is usually precipitated by an allergy or mild upper respiratory infection. It can be quite alarming, both because of the noise of the cough and because it usually comes on suddenly in the middle of the night. A child may go to sleep with a mild cold and wake up a few hours later, gasping for air. In addition, the child may have a cough that sounds like a seal barking, and will have a hoarse voice. Children with spasmodic croup normally do not have a fever .

Spasmodic croup can sometimes be difficult to differentiate from viral croup. Although spasmodic croup is associated with the same viruses that cause viral croup, spasmodic croup tends to recur and may be an indication of some type of allergic reaction instead of a direct infection.


The viruses causing croup are highly contagious and easily transmitted between individuals through sneezing and coughing. It is usually transmitted via the respiratory route, entering through the nose and nasopharynx.


Croup accounts for about 15 percent of all respiratory tract infections in children seen by physicians. It typically is seen in late fall and winter, and primarily occurs in children aged six months to three years. It has an annual peak incidence of 50 new cases per 1,000 children during the second year of life. Males are twice as likely as females to get the disease. The incidence decreases significantly after age six.

Causes and symptoms

Croup is most commonly brought on by a viral infection. The parainfluenza viruses (types 1, 2, and 3) are the most frequent causes of croup, accounting for approximately 75 percent of all cases diagnosed. Human parainfluenza virus 1 (HPIV-1) is the most common cause. Croup may also be caused by influenza A and B, adenovirus, measles , and respiratory syncytial virus (RSV). Other possible causes of croup are bacteria, inhaled irritants, allergies , and acid reflux.

The following are usually true of viral croup:

  • It commonly occurs in individuals between the ages six months to six years.
  • Stridor, and the classic barking cough are usually present.
  • The child may have a fever.
  • Wheezing may be present.
  • It usually lasts two to seven days.

The following items are characteristic of spasmodic croup:

  • The symptoms come on suddenly, often in the middle of the night.
  • Stridor occurs along with the barking cough.
  • It typically lasts two to four hours.

When to call the doctor

Most cases of croup can be safely managed at home, but parents should call their child's doctor for advice, even if it is in the middle of the night. Call 911 for emergency help if any of the following is true:

  • The croup is possibly caused by an inhaled object or by an insect sting.
  • The child is drooling.
  • The child has blue lips or skin.
  • The child has a very high fever.
  • The child is very anxious, has rapid breathing, and/or is struggling to get a breath.
  • The child insists on sitting up or complains of a sore throat and is drooling. This is a possible indication that he or she may have a disease called epiglottitis , which is potentially life-threatening.
  • The child makes a whistling sound that gets louder with each breath.
  • The child has stridor when resting.


The diagnosis of croup is usually made based on the description of symptoms by the parent, as well as a physical examination. Sometimes other studies, such as x rays , may be required. The doctor may note chest retractions with breathing and may hear wheezing and decreased breath sounds when listening to the chest with a stethoscope. Sometimes a foreign object or narrowing of the trachea is seen on a neck x ray.


The most important part of treating patients with croup is maintaining an open airway. If a child wakes up in the middle of the night with croup, he or she should be taken to the bathroom. The door should be closed and the shower turned on to allow the bathroom to steam up. The parent should then sit in the steamy bathroom with the child. The moist, warm air should assist the child in breathing within 15 to 20 minutes, though the child will still have the barking cough. For the rest of that night and for two to three nights following, a humidifier or cold-water vaporizer should be placed in the child's room. If another attack of croup recurs that night or the next, the steam treatment should be repeated. If the steam does not work, sometimes taking the child outside, where he or she can inhale the cool, moist night air will be enough to improve breathing. Though a study in the early 2000s cast some doubt on the efficacy of using steam or mist, it does seem to be helpful for most children with croup. Parents may also give acetaminophen to reduce fevers and increase the child's comfort level. Cough medicines should usually be avoided.

Several other treatments are possible if the croup is severe enough to warrant the child's being seen by a physician. Aerosolized racemic epinephrine as well as oral dexamethasone (a steroid) may be used to help shrink the upper airway swelling. A bacterial infection will require antibiotics. If the airway becomes increasingly obstructed, the child may require intubation (the placing of a tube through the nose or mouth through the larynx into the main air passage to the lungs.) If the patient is dehydrated, intravenous fluids will be administered.


Croup is normally a self-limiting disease with an excellent prognosis. Only a few who are diagnosed require hospitalization , and less than 5 percent require intubation. If proper airway management is maintained, death is rare. There is some speculation that children with a history of croup may be at a higher risk for developing asthma , but the evidence was not clear as of 2004.


The best way to prevent croup is to prevent the causative infections. Parents should practice excellent hand washing, especially during the cold and flu season, and avoid close contact with anyone who has a respiratory infection.

Parental concerns

The onset of croup can be frightening, especially when it comes on suddenly. Parents can help their child by not panicking or appearing anxious, as this may increase anxiety in the child, which can worsen symptoms. If they are at all unsure about how their child is responding to home treatment, parents should not hesitate to seek medical advice or treatment, no matter the time of day or night.

See also Influenza .



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Knutson, Doug, and Ann Aring. "Viral Croup." American Family Physician 69 (February 1, 2004): 3, 535–40.

"Patient Education Guide: What to Do When Your Child Has Croup." Journal of Respiratory Diseases 23 (March 2002): 23, 192–5.


American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site:


"Croup." MedlinePlus. Available online at (accessed January 11, 2005).

Deanna M. Swartout-Corbeil, RN


Epiglottitis —Inflammation of the epiglottis, most often caused by a bacterial infection. The epiglottis is a piece of cartilage behind the tongue that closes the opening to the windpipe when a person swallows. An inflamed epiglottis can swell and close off the windpipe, thus causing the patient to suffocate. Also called supraglottitis.

Larynx —Also known as the voice box, the larynx is the part of the airway that lies between the pharynx and the trachea. It is composed of cartilage that contains the apparatus for voice production–the vocal cords and the muscles and ligaments that move the cords.

Retractions —Tugging-in between the ribs when breathing in.

Stridor —A term used to describe noisy breathing in general and to refer specifically to a high-pitched crowing sound associated with croup, respiratory infection, and airway obstruction.

Trachea —The windpipe. A tube composed of cartilage and membrane that extends from below the voice box into the chest where it splits into two branches, the bronchi, that lead to each lung.

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