Also called: Laryngotracheobronchitis, Laryngotracheitis

Reviewed By:
Rafiu Ariganjoye, M.D., MBA, FAAP
Robert Daigneault, M.D


Croup is a common respiratory illness that primarily affects infants and young children. It involves inflammation of the voice box (larynx) and windpipe (trachea), resulting in breathing difficulties and distinctive symptoms such as a cough that sounds like a seal barking.

Croup is most common between the ages of 3 months and 5 years, and symptoms are usually the most severe in patients under 3 years old. It occurs more often in boys than girls. Croup can occur year round, but is more common in colder weather. Children who are born prematurely or who have a history of respiratory problems may be more susceptible to croup or a recurrence of croup.

Most cases of croup are caused by a viral infection, according to the American Academy of Family Physicians. Croup is less commonly caused by bacteria, allergies, inhaled irritants or acid reflux. Symptoms may be worse at night, but are generally mild and go away on their own.

The usual course of treatment of croup is therapy aimed at alleviating symptoms. At home, this includes inhaling moist air, such as from shower steam or a cool mist humidifier, or taking a child outside for cool air. Avoiding smoke, increasing fluids and keeping the child calm also helps.

Croup symptoms can be disconcerting for both parents and children. Parents may want to seek medical attention the first time a child displays symptoms, especially if they occur in the middle of the night. They may call their pediatrician’s on-call service or visit a hospital emergency room. When symptoms are severe or persist, parents should seek immediate medical attention for their child. An evaluation may include a description of the child’s symptoms and a physical examination. A physician may be able to identify croup by listening to a child cough over the phone. Certain medications may be prescribed to alleviate the child’s symptoms. In rare cases, children with croup may need to be hospitalized. This may be done for observation, or when symptoms indicate significant breathing problems or dehydration.

Most cases of croup are contagious. Croup can be prevented by practicing good hygiene (e.g., frequent handwashing). There is currently no vaccine available that prevents most cases of croup, although several existing vaccines for other conditions can protect children against the most severe cases of croup.

About croup

Croup is a respiratory illness that causes inflammation and swelling of the respiratory system. It is most common among infants and young children (3 months to 5 years old) because their small airways are more likely to narrow as a result of inflammation. This leads to the breathing difficulties (e.g., barking cough, noisy and labored breathing) that are the signature symptoms of croup.  

The areas typically inflamed in cases of croup are the trachea (also referred to as the windpipe) and larynx (voice box).

The trachea is the main passageway for air and leads from the larynx to the lungs. The larynx contains two elastic bands of muscle tissue called vocal cords. This tissue vibrates as air passes through it, producing sound. In the chest, the trachea splits into two tubes called bronchi, with one going to each lung.

The inflammation of croup can cause swelling of the larynx or trachea. This swelling lessens the space for air to travel to the lungs, making breathing more difficult or noisier. Coughing usually occurs in an attempt to clear the airways.

Croup is a common respiratory illness among infants and young children. It is responsible for 15 percent of all respiratory tract infections seen by pediatricians, according to the American Academy of Family Physicians. A similar inflammation of the larynx in older children or adults would cause laryngitis (inflammation of the larynx), which is characterized by hoarseness.

Although most cases of croup involve mild symptoms that resolve on their own, symptoms can sometimes be severe enough to require hospitalization. It is estimated that croup causes more than 40,000 hospitalizations each year in the United States. Many of these may be related to parents visiting a hospital emergency room at night when their child’s physician is not available. In rare cases, severe croup symptoms can lead to respiratory arrest and death.

Complications may also sometimes occur as a result of croup. These include:

  • Bacterial tracheitis. A bacterial infection of the trachea, just below the vocal cords, that can occur with viral croup. Thick pus is produced as a result of this infection, which can obstruct the airway. Hardened tissue, small collections of pus and ulcers can occur along the surface of the trachea. Antibiotic treatment is necessary (since the infection is bacterial) and hospitalization may be required. Bacterial tracheitis occurs in a small number of patients.
  • Dehydration or malnutrition. An infant or child with croup may stop eating or drinking when it becomes difficult to breathe. Dehydration and malnutrition may require hospitalization.
  • Atelectasis. Collapse of part or all of a lung that may occur when the airway is blocked. This may be life-threatening in infants and small children.
  • Pneumonia or ear infections. In rare cases, viral croup may spread to other areas of the body, resulting in pneumonia and ear infections.

Types and differences of croup

Croup is sometimes also referred to as viral croup or infectious croup because most cases of croup are caused by viruses and are contagious.

Croup may be distinguished by the areas in the respiratory system that are affected by inflammation. Both of the following terms are sometimes used interchangeably with croup:

  • Laryngotracheitis. Inflammation of the larynx (voice box) and trachea (the windpipe leading from the larynx to the lungs).
  • Laryngotracheobronchitis (LTB). Inflammation of the larynx, trachea and bronchi (the airways that connect the trachea to the lungs).  

Croup may be considered a type of laryngitis (inflammation of the larynx) that occurs in children. In most cases, it does not involve obstruction of the airway or breathing difficulties. The primary symptom of laryngitis is hoarseness.

A less common type of croup is called spasmodic croup. In these cases, croup symptoms occur suddenly and spontaneously, without being preceded or accompanied by cold or flu-like symptoms (e.g., stuffy or runny nose, fever). Spasmodic croup may be associated with allergies and psychological factors more so than viruses, although viruses may cause spasmodic croup.

Croup can sometimes be mistaken for a serious medical emergency called epiglottitis. This is an infection of the epiglottis, the flap of cartilage that closes over the larynx during swallowing, preventing food from entering the trachea. Symptoms of epiglottitis are similar to croup, except there is no barking cough and it may also include drooling and difficulty swallowing. Epiglottitis is rare but may be life-threatening if the trachea becomes completely obstructed.

Risk factors and causes of croup

Most cases of croup are caused by a viral infection – specifically, human parainfluenza viruses (HPIVs). Seventy-five percent of all cases of croup are caused by HPIVs, according to the American Academy of Family Physicians. HPIVs are extremely common and include viruses that cause the common cold. Other viruses that may cause croup include respiratory syncytial virus (RSV), adenovirus, measles and influenza. Croup is less commonly caused by bacteria, allergies, inhaled irritants or acid reflux.

A number of factors can increase the risk of croup, including:

  • Age. Infants and children are most susceptible to croup. Croup most commonly occurs between the ages of 3 months and 5 years. Although the disease is rare after age 6, it may occur at any age. The risk of croup peaks when children are about 2 years old. Symptoms are most severe in children under 3 years old, because inflammation is more likely to impair breathing when the trachea (windpipe) is small. After age 3, the trachea has grown enough so symptoms do not usually include breathing difficulties.   
  • Premature birth or narrow upper airways. Children who are born prematurely or who have narrow upper airways may be more likely to suffer from the symptoms of croup. Croup is more likely to recur among this population as well.
  • History of respiratory problems. Children who experience breathing difficulties caused by other respiratory conditions (e.g., lung disease, asthma) may develop severe symptoms of croup and require hospitalization. They are also more likely to experience a recurrence of croup.
  • Gender. Boys are affected by croup more often than girls.
  • Non-summer seasons. Although it is possible for croup to occur year-round, the illness is most common from fall through spring.

Diagnosis methods for croup

Diagnosis of croup by a physician is likely to begin with a parent’s description of their child’s symptoms. A complete medical history may be taken, including any history of croup or other breathing problems (e.g., asthma).

The physician is also likely to perform a physical examination of the child. The physician may use a stethoscope to listen to the chest area in order to detect any noise when breathing, which may indicate croup or other respiratory problem. The physician may also look for signs of chest retraction (the sucking in of the chest wall when breathing) that indicates respiratory difficulty. The throat may also be examined for redness of the epiglottis (the flap of cartilage over the voice box) that may become infected and inflamed.   

A physician may be able to identify croup by simply listening to the child cough, since a barking cough is the hallmark of croup. In some cases, this may be done by listening to the child cough over the phone.

Physicians may use the Westley croup score to identify the severity of croup. Although widely used to evaluate course of treatment, its clinical efficacy has not been extensively studied. Physical signs evaluated using this method include levels of consciousness, cyanosis (when the skin turns bluish in color from a lack of oxygen), stridor (high-pitched squeaking when inhaling), air entry and chest retraction. Scores range from 0 to 17 and can help identify whether croup symptoms are mild (score of 3 or less), moderate (score between 3 and 6) or severe (greater than 6).  

X-rays may also be performed. A neck x-ray may be performed to rule out breathing difficulty caused by a foreign object lodged in the throat. X-rays may also be used to view the circumference of the trachea (windpipe), to see if there has been any significant narrowing due to inflammation or other causes. When a child has croup, an x-ray will typically show the top of the child’s airway narrowing to a point called a steeple sign.

The use of blood tests to diagnose croup is rare. In some cases, these tests may help determine the course of treatment – such as the use of antibiotics if a bacterial infection is also present. Although not necessary for the treatment of viral croup, a throat culture may help identify the type of virus responsible for the infection.

Treatment options for croup

Most cases of croup are caused by a viral infection with symptoms that are mild and resolve on their own within a week. Treatment is usually not necessary, except for therapies aimed at relieving symptoms.

The following may help relieve mild symptoms of croup:

  • Keeping the child calm. Stress, agitation or fear can cause an infant or child to breathe faster, aggravating the breathing difficulties of croup. Cuddling, reading a bedtime story or other soothing behaviors can help keep the infant or child calm, which can help improve breathing.
  • Sitting upright. Breathing is easier in the upright position. Infants can be placed in a car seat to aid breathing.
  • Inhaling moist or cool air. Ten minutes or so in a steamy bathroom or in the cool (outdoor) night air may provide some relief. Breathing in moist or cool air through the mouth may help shrink swollen airway tissue, aiding breathing – although a barking cough may remain. A cool mist humidifier (hot air devices may burn the skin), riding in a car with the windows down (to bring in cool air) or breathing through a warm, wet washcloth gently placed over the nose and mouth may also help. The use of a croup tent is obsolete at home or in the hospital, and should be avoided, since it may make an infant or child more anxious and actually worsen symptoms. However, despite its continued widespread use, little clinical evidence exists to support the efficacy of inhaling moist or cool air.
  • Medications. Pain relievers such as acetaminophen and ibuprofen may help relieve chest discomfort from coughing and lower fever, if necessary. However, aspirin should never be given to a child because of the risk of developing a serious condition called Reye syndrome.
  • Drinking plenty of fluids. Children with croup may find cool or warm fluids soothing. This can include non-citrus juice, milk or soup. Carbonated or citrus drinks should be avoided because carbonation and citric acid can irritate inflamed tissue.
  • Keeping the child away from smoke. Cigarette smoke can aggravate a child’s croup symptoms, making breathing more difficult.

Parents should consult a physician before providing any type of cough medication to their infant or child with croup. All medications, even over-the-counter cough suppressants, have side effects that may be dangerous for infants and young children. In addition, cough syrups do not affect the larynx (voice box) or trachea (windpipe), where croup inflammation is located, and they may prevent the release of mucus from the area. Cough drops may pose a choking hazard for young children.

In the event that symptoms persist or increase in intensity, parents should take their child to see a physician, preferably a pediatrician. A physician may prescribe the following treatments to relieve the symptoms of croup:

  • Corticosteroids. Steroid medications that help reduce inflammation and can be an effective method of treating mild, moderate and severe symptoms of croup. They are available in a single dose in oral, inhalant and injectable forms. It may be several hours before this medication takes effect, although symptom improvement is usually seen within six hours. Side effects are rare, but may include a worsening of chickenpox in children recently exposed to the chickenpox virus.
  • Medicated aerosol treatments. Delivered in mist form, these medications (such as epinephrine, a hormone also known as adrenaline) are used to treat moderate to severe symptoms of croup. Symptoms generally improve within 30 minutes of treatment. However, effects of this medication usually wear off within two hours. Thus, a dose of corticosteroids is necessary, and the child should be observed for at least four hours after the inhalation of epinephrine to prevent a rebound of stridor and respiratory distress. Side effects are extremely rare.
  • Antibiotics. Required when a bacterial infection (superinfection) develops as a result of viral croup. Antibiotics have no effect on most cases of croup, which are viral in origin.

When symptoms are severe, an infant or child may need to be hospitalized. This may be done simply for observation, or to provide the following treatment:

  • Oxygen and humidity may be administered via an oxygen tent placed over a crib. This may be necessary in cases where there is moderate or severe breathing problems and the child is not getting enough oxygen (e.g., skin is turning bluish in color from lack of oxygen). A mixture of helium and oxygen (called heliox) may also be administered, although some studies have indicated that the use of heliox may be no more effective than the use of oxygen alone.
  • Intubation (tube inserted via nose or mouth, through the larynx and into the trachea) to bypass areas of swelling and aid breathing. Intubation is seldom necessary.
  • Intravenous (I.V.) feeding or fluids. Infants or children who are unable to eat, or have lost significant fluids due to fever or rapid breathing, may need to receive nutrition or fluids via I.V.

Prevention methods for croup

Most cases of croup are caused by a viral infection and are contagious (easily transferred from person to person). The virus can spread via contact with secretions in the air as the result of coughing, sneezing or breathing. It can also be transferred via contaminated surfaces, such as tissues, door handles, countertops or skin.

Good hygiene (e.g., frequent handwashing) is the primary method available to avoid the spread of croup. This includes washing hands after sneezing, coughing or nose-blowing, as well as after caring for anyone with a viral illness. Avoid close contact between children and people who are sick (e.g., adults with a cold should avoid kissing or handling infants and small children).

Personal items such as beverage containers, eating or cleansing utensils (e.g., spoons, toothbrushes) should not be shared to avoid contamination. Toys that have been chewed or sucked on by young children with a cold should be washed with soap and water. Promptly dispose of used tissues.

It can be difficult to completely avoid the viruses that can cause croup. Adults or older children carrying a virus that can cause croup may not display symptoms. Also, viruses are often spread in the early stages of the disease, before symptoms appear.

There are currently no vaccines designed specifically to prevent most cases of croup. However, some vaccines for other conditions protect children from the most dangerous forms of croup. These vaccines include:

  • Diphtheria
  • Haemophilus influenzae (HiB)
  • Measles

Breastfeeding appears to play a role in the prevention of croup. Research indicates that infants acquire certain antibodies via breast milk that can help protect them against croup.

Questions for your doctor regarding croup

Preparing questions in advance can help parents have more meaningful interactions with a physician regarding their child’s treatment options. The following questions related to croup may be helpful:

  1. My child has a cough that sounds like a seal barking – does this positively mean he/she has croup? Do I need to bring him/her to see you for a diagnosis?
  2. What do I do when my child has croup?
  3. How can I tell if my child’s symptoms are mild or severe?
  4. If the symptoms remain mild, what can I do at home to make my child more comfortable?
  5. Which change in symptoms should I report to you? At what point should we seek emergency medical treatment for my child?
  6. Could my child’s symptoms be the result of an airway obstruction, insect bite or allergy? How can I know this?  What do I do if this is the case?
  7. Does the presence of a high-pitched, squeaking noise when my child inhales mean he/she can’t breathe?  How serious is this?  What do we do when this happens?
  8. Is my child’s croup caused by a viral or bacterial infection?
  9. Is there anything else that may be causing croup in my child?
  10. My child’s croup symptoms stopped after a few days. Should I bring him/her in for a follow-up examination?
  11. Is my child at risk to experience croup again in the future? Why?
  12. Will a history of breathing problems or asthma affect the likelihood of my child getting croup again in the future?
  13. For how long will my child be at risk for a recurrence?
  14. Is there anything I can do to prevent a recurrence of croup in my child?
  15. Are there vaccines to help prevent croup in children? Which ones do you recommend and when can my child get them? 
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