The term croup is used to describe a variety of respiratory illnesses in children. It mostly occurs in infants and young children between six months and three years of age, and is rarely seen in children older than six years. It is most commonly seen in the fall and early winter months. It is slightly more common in boys compared to girls.
The most common cause of croup is a viral infection (such as parainfluenza or influenza) that leads to swelling of the larynx (voice box) and trachea (windpipe). However, infection with these viruses is common and most children with these infections do not develop croup.
The viruses infect the nose and throat initially, and then spread along the upper respiratory tract (back of the throat) to the larynx and trachea (windpipe) (figure 1). As the infection progresses, the top part of the trachea becomes swollen, which narrows the space available for air to enter the lungs. This leads to the symptoms of croup. (See 'Croup symptoms' below.)
Bacterial infection of the same areas can occur during the viral infection, but this does not happen very often. Bacterial coinfection is usually more severe and requires a different treatment than a viral infection.
The primary symptoms of croup are a “barking cough” and hoarseness. Croup is usually mild and lasts less than one week, although it is possible for symptoms to become severe and life threatening. Symptoms are usually worse at night. The more severe cases are due to difficulty breathing caused by swelling in the upper part of the windpipe. Symptoms usually start gradually, beginning with nasal irritation, congestion, and runny nose. Difficulty breathing can develop and become worse during the 12 to 48 hours after congestion and barking cough begin.
Most children develop a fever, which may range from mild (100.4ºF or 38ºC) to very high (104ºF or 40.5ºC). The fever itself does not cause them harm (see "Patient information: Fever in children (The Basics)"). The information in the Table describes how to take a child's temperature (table 1).
Other symptoms such as rash, eye redness (called conjunctivitis), and swollen lymph nodes may develop, depending upon the virus causing the illness. Dehydration can occur if the child is not able to drink enough fluids.
As the upper airway narrows, high-pitched, noisy breathing (called stridor) develops and the child may breathe faster; the child may become restless or anxious (agitated) as breathing becomes more difficult. Agitation can increase the narrowing, which leads to even more difficulty breathing and further agitation. The effort required to breathe faster and harder is tiring, and the child may become exhausted and unable to breathe on his or her own in severe cases.
Low oxygen levels (called hypoxia) and blue-tinged skin (called cyanosis) can develop as airflow to the lungs is restricted. Cyanosis may first be noticed in the fingers and toenails; ear lobes; tip of the nose, lips, tongue; and inside of the cheek.
Contagiousness — Croup is caused by viruses that can be spread easily through coughing, sneezing, and respiratory secretions (mucus and droplets from coughing or sneezing). Children with croup should be considered contagious for three days after the illness begins or until the fever is gone.
Severity of croup — Croup can be very mild or very severe, depending on how difficult it is for the infant or child to pull air into the lungs. The size (diameter) of the windpipe (which is normally smaller in infants) and degree of narrowing due to swelling are important determinants of severity. Croup may become more severe when a child becomes agitated or upset.
A child with moderate to severe croup may have to struggle to breathe in ways that can be frightening for both the child and parent (or other caregivers).
Mild croup — A child with mild croup generally is alert and without blue-tinged skin or retractions (sucking in of the skin around the ribs and the top of the sternum) (figure 2). There may be a barking cough. Stridor (high-pitched, noisy breathing) is not present at rest but may be present as the child coughs or cries. A child with mild croup can develop more severe symptoms intermittently throughout the course of the illness, especially during the evening hours.
Moderate croup — A child with moderate croup may have stridor (high-pitched, noisy breathing) and retractions (sucking in of the skin around the ribs and the top of the sternum) at rest, may be slightly disoriented or agitated, and may have moderate difficulty breathing.
Severe croup — A child with severe croup has stridor and retractions at rest. Retractions are a sign of severe croup. These include inward movement (sucking in) of the sternum (breast bone) or skin between the ribs as the child struggles to take a breath. The child may appear anxious, agitated, or fatigued. Cyanosis (blue-tinged skin) is common, initially only when the child is moving or crying, but progressively worsening so that it is present even when the child is resting.
Croup is usually diagnosed based upon the child's symptoms and signs, including a barking cough and stridor, especially if these findings occur during the fall and winter months. X-ray and laboratory testing are rarely needed.
The healthcare provider who examines your child must determine if your child is likely to worsen and require care in an emergent care setting.
The treatment of croup depends upon the severity of symptoms and the risk of rapid worsening; children with mild symptoms who have no risk factors for severe croup generally are treated at home, while a child with moderate to severe symptoms or who is at risk for rapid worsening should be treated in an emergency department.
Mild croup — Most children with croup have mild symptoms and can be successfully treated at home. This includes using mist from a humidifier or sitting with the child in a bathroom (not in the shower) filled with steam generated by running hot water from the shower. A parent should stay with the child during mist treatment; a favorite book or lullaby may help to decrease the child's anxiety and prevent crying, which can worsen stridor.
Hot steam humidifiers should be avoided because of the risk of burns. If the child's stridor does not improve during the mist treatment, the parent should contact their child's healthcare provider.
Other suggestions for home treatment of mild croup include:
- Allow the child to breathe cool air during the night by opening a window or door.
- Fever can be treated with an over-the-counter medication such as acetaminophen or ibuprofen. (See "Patient information: Fever in children (Beyond the Basics)".)
- Coughing can be treated with warm, clear fluids to loosen mucus on the vocal chords. Warm water, apple juice, or lemonade is safe for children older than four months. Frozen juice popsicles also can be given.
- Smoking in the home should be avoided; smoke can worsen a child's cough.
- Keep the child's head elevated. An infant can be placed in a car seat. A child may be propped up in bed with an extra pillow. Pillows should not be used with infants younger than 12 months of age.
- Parents may sleep in the same room with their child during an episode of croup so that they will be immediately available if the child begins to have difficulty breathing.
Emergent care — Parents should seek immediate medical attention if, at any time, a child develops features of worsening or severe croup. (See 'When to seek help' below.)
Medications — A child with mild croup who is seen in a healthcare provider's office or the emergency department may be given mist treatment in addition to a single dose of a glucocorticoid medication. The most frequently used glucocorticoid is dexamethasone, which can be given as an oral syrup or as an intravenous (IV) or intramuscular (IM) injection (depending upon which treatment is easiest for the child).
Dexamethasone provides long-lasting and effective treatment for mild croup, as well as for moderate and severe croup. It works to decrease swelling of the larynx, usually within six hours of the first dose. For a child with mild croup, dexamethasone can reduce the need for a repeat visit to the emergency department or provider's office and can improve the child's ability to sleep (by easing the work of breathing).
Budesonide is another glucocorticoid medication that is sometimes used. It is administered by inhalation. Other oral glucocorticoids may be prescribed as well.
Moderate to severe croup — Moderate to severe croup should be evaluated in an emergency department or clinic capable of handling urgent respiratory illnesses. Severe croup is a life-threatening illness and treatment should not be delayed for any reason.
The treatment used depends upon the type and severity of signs and symptoms, but may include one or more of the following:
- Humidified air or oxygen (if oxygen is necessary).
- Intravenous fluids may be needed if the child is dehydrated as a result of fever or rapid breathing, both of which increase the body's loss of fluids. Difficulty breathing can discourage a child from drinking, which can increase the risk of dehydration.
- Monitoring of oxygen levels, breathing and heart rate, skin color (normal versus blue-tinged), and level of alertness are used to measure the child's status and response to treatment. A child who fails to improve or who improves slowly may need further treatment.
- Placement of a breathing tube in the throat is rarely needed for children with severe croup; less than 1 percent of children seen in the emergency room require intubation.
Dexamethasone — Dexamethasone is the most frequently used medication for the treatment of all types of croup; it is a glucocorticoid that provides long-lasting and effective treatment. It works by decreasing swelling of the larynx, usually within six hours of the first dose. It can reduce the need for a repeat visit to the emergency department or provider's office, decrease the time spent in the emergency department, and decrease the dose of other medications (eg, epinephrine).
It can be given as an oral syrup or as an intravenous (IV) or intramuscular (IM) injection (depending upon which treatment is easiest for the child). Most children only require one dose, and serious side effects are rare.
Epinephrine — Epinephrine, commonly referred to as "adrenaline", is given by nebulizer (an inhaled mist) to children with moderate to severe croup. It also reduces swelling in the airway and begins to work faster than dexamethasone. It works for a short time period (two hours or less), and may be given every 15 to 20 minutes for severe symptoms. Retreatment may be needed after two hours if symptoms return after an initial response. When such "rebound" symptoms occur, it is usually within two to four hours after the treatment.
Side effects of epinephrine include rapid heartbeat. Serious side effects are rare. Children who are given epinephrine must be monitored for three to four hours after the last dose to ensure that symptoms of airway blockage do not return.
Other therapies — Other therapies, such as antibiotics, cough medicines, decongestants, and sedatives, are not routinely recommended for children with croup. Antibiotics do not treat viruses, which cause most cases of croup. Cough medicines and decongestants have not been proven to be helpful, and sedatives can mask symptoms of low blood oxygen and difficulty breathing.
Complications of croup are uncommon. Symptoms of croup resolve in most children within two days, but can persist up to one week. Fewer than 5 percent of children with croup require hospitalization.
Unfortunately, there is no way to prevent croup. There are no vaccines against most of the viruses that can cause croup.
Simple hygiene measures can help to prevent infection with the viruses that can lead to croup. These measures include:
- Frequent hand washing with soap and water. Hands should ideally be wet with water and plain or antimicrobial soap, and rubbed together for 15 to 30 seconds. Special attention should be paid to the fingernails, between the fingers, and the wrists. Hands should be rinsed thoroughly and dried with a single-use towel.
- Use of alcohol-based hand rubs. These are a good alternative for disinfecting hands if a sink is not available. Hand rubs should be spread over the entire surface of hands, fingers, and wrists until dry, and may be used several times. Hand rubs are available as a liquid or wipe in small, portable sizes that are easy to carry in a pocket or handbag. When a sink is available, visibly soiled hands should be washed with soap and water.
- Avoid close contact with other adults and children with upper respiratory infection when possible. This may be difficult, especially when in public, but parents can try to limit direct contact. In addition, infants or children who are sick should not be sent to day care or school as this can potentially cause others to become ill.
- Yearly vaccination for the influenza virus is recommended for individuals older than six months. Flu vaccines are usually given in the fall and winter months. (See "Patient information: Influenza prevention (Beyond the Basics)".)
WHEN TO SEEK HELP
If, at any time, a child develops features of worsening or severe croup, the parent should seek immediate medical attention. This includes:
- Difficulty breathing
- Pale or blue-tinged skin
- Severe coughing spells
- Drooling or difficulty swallowing
- Inability to speak or cry due to difficulty taking a breath
- A whistling sound with breathing, or noisy-high pitched breathing while sitting or resting
- Sucking in of the skin around the ribs and top of the sternum with breathing
Parents should not attempt to drive their child to the hospital if the child is severely agitated, has blue-tinged skin, is struggling to breathe, or is excessively drowsy (lethargic); emergency medical services should be called, available in most areas of the United States by dialing 911.
A parent should call their child's healthcare provider if:
- A fever (temperature higher than 100.4ºF or 38ºC) lasts more than three days.
- Symptoms of mild croup last longer than seven days.
- There are questions or concerns about the child's condition.
- Croup is a respiratory illness usually caused by a virus. As the illness progresses, the trachea becomes swollen, which narrows the space available for air to enter the lungs.
- The viruses that cause croup can be spread easily through coughing, sneezing, and respiratory secretions (mucus, droplets from coughing or sneezing). Children with croup should be considered contagious for three days after the illness begins, or until the fever is gone.
- Croup is usually mild, although it is possible for symptoms to become severe and life-threatening. Symptoms usually start gradually, beginning with nasal irritation, congestion, and a runny nose, which may worsen after 12 to 48 hours to include difficulty breathing, a "barking cough", and hoarseness. Symptoms of croup usually resolve within two days, but can persist up to one week (with gradual improvement during this time).
- If, at any time, a child develops features of worsening or severe croup, the parent should seek immediate medical attention. Features of severe croup include:
- Difficulty breathing
- Pale or blue-tinged skin, especially in the lips, fingers, toes, or earlobes
- Severe coughing spells
- Drooling or difficulty swallowing
- Inability to speak or cry due to difficulty taking a breath
- A whistling sound with breathing or noisy-high pitched breathing while sitting or resting
- Sucking in of skin around the ribs with breathing
Parents should not attempt to drive their child to the hospital if the child is severely agitated, cyanotic, struggling to breathe, or excessively drowsy (lethargic); emergency medical services should be called, available in most areas of the United States by dialing 911.
- Mild croup can usually be treated at home. Home treatment includes using mist from a humidifier or by sitting with the child in a bathroom filled with steam generated by running hot water from the shower. Hot steam humidifiers should be avoided because of the risk of burns.
- Moderate to severe croup should be evaluated in an emergency department or clinic capable of handling urgent respiratory illnesses. Severe croup is a life-threatening illness and treatment should not be delayed for any reason.
- Other therapies, such as antibiotics, cough medicines, decongestants, and sedatives, are not recommended for children with croup. Antibiotics do not treat viruses, which cause most cases of croup.
- Smoking in the home should be avoided. Parents may sleep in the same room with their child during an episode of croup so that they will be immediately available if the child begins to have difficulty breathing.
WHERE TO GET MORE INFORMATION
Your child's healthcare provider is the best source of information for questions and concerns related to your child's medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Croup (The Basics)
Patient information: Cough in children (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Fever in children (Beyond the Basics)
Patient information: Influenza symptoms and treatment (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Approach to chronic cough in children
Approach to the management of croup
Assessment of stridor in children
Causes of chronic cough in children
Clinical features, evaluation, and diagnosis of croup
Emergent evaluation of acute upper airway obstruction in children
Etiology and management of hoarseness in children
Parainfluenza viruses in children
Pharmacologic and supportive interventions for croup
The following organizations also provide reliable health information.
- National Library of Medicine
(www.nlm.nih.gov/MEDLINEPLUS/ency/article/000959.htm, available in Spanish)
- American Academy of Pediatrics