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CROUP OVERVIEW — 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 less commonly seen in children older than six years. It is usually seen in the fall and early winter months. It is slightly more common in boys compared with girls.
CROUP CAUSES — 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 bottom part of the larynx and top part of the trachea become swollen, which narrows the space available for air to enter the lungs (figure 2). 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.
CROUP SYMPTOMS — 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 stuffiness 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 (100.4°F or 38°C) to very high (104°F or 40.5°C). The fever itself does not cause them harm (see "Patient education: 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, and 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 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 3). 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 worsens until it is present even when the child is resting.
CROUP DIAGNOSIS — 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-rays and laboratory testing are rarely needed.
The health care provider who examines your child must determine if your child is likely to worsen and require care in an emergent care setting.
CROUP TREATMENT — 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 health care 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 education: Fever in children (Beyond the Basics)".)
●Coughing can be treated with warm, clear fluids to loosen mucus on the vocal cords. 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. 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.
Emergency 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 health care 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 glucocorticoids are dexamethasone and prednisolone, which are usually given as an oral syrup. Dexamethasone can also be given intravenously (IV) or with an intramuscular (IM) injection, especially if the child is vomiting and not able to keep liquids down.
Glucocorticoids work to decrease swelling of the larynx, usually within six hours of the first dose. For a child with mild croup, glucocorticoids may 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).
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 severity of signs and symptoms but may include one or more of the following:
●Humidified air or oxygen (if oxygen is necessary).
●IV 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 department 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 IV or 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 play a role in treating croup because croup is caused by viruses and antibiotics do not treat viruses. Cough medicines and decongestants have not been proven to be helpful, and sedatives can mask symptoms of low blood oxygen and difficulty breathing.
CROUP'S TYPICAL COURSE — Symptoms of croup resolve in most children within two days but can persist up to one week. Complications are uncommon.
Fewer than 5 percent of children with croup require hospitalization. Children are usually hospitalized when:
●Oxygen therapy is needed to keep the child's oxygen levels in a safe range
●Croup is complicated by severe dehydration requiring intravenous fluid therapy
●Multiple doses of inhaled epinephrine are needed to provide relief
●Severe symptoms persist despite initial treatment, especially if the child's breathing is becoming fatigued
Some children may require observation in the hospital for only a few hours to half a day. Others may stay in the hospital for a day or two. It is unusual to require more than a two-day hospitalization for croup. If this happens, an additional evaluation may be performed to assess for other causes of stridor and breathing difficulty. This may include X-rays and/or consultation with an ear, nose, throat specialist.
CROUP PREVENTION — Simple hygiene measures can help to prevent infection with the viruses that lead to croup. There are no vaccines against the most common viruses that cause croup. However, vaccines are recommended for some viruses that can cause croup (influenza, coronavirus disease 2019 [COVID-19]).
Hygiene and other preventive measures include:
●Frequently wash hands 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 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 daycare or school, as this can potentially cause others to become ill.
●Ensure the child is vaccinated – Vaccinations against influenza and COVID-19 are recommended for individuals older than six months. (See "Patient education: Influenza prevention (Beyond the Basics)" and "Patient education: COVID-19 vaccines (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 health care provider if:
●A fever (temperature higher than 100.4°F or 38°C) lasts more than three days
●Symptoms of mild croup last longer than seven days
●There are questions or concerns about the child's condition
SUMMARY
●What is croup? – 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 (figure 2).
●How is croup spread? – 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.
●What are the signs of croup? – 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).
●When to seek help – 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, 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.
●How is croup treated?
•Mild croup – 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. 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.
•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 severity of signs and symptoms. It may include:
-Humidified air or oxygen
-Administration of a glucocorticoid medication (usually dexamethasone)
-Nebulized breathing treatments (epinephrine)
•Treatments that are not recommended – Other therapies, such as antibiotics, cough medicines, decongestants, and sedatives are not recommended for children with croup. Antibiotics do not play a role because croup is caused by viruses and antibiotics do not treat viruses.
WHERE TO GET MORE INFORMATION — Your child's health care 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 website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care 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 education: Croup (The Basics)
Patient education: 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 education: Fever in children (Beyond the Basics)
Patient education: 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
Management of croup
Assessment of stridor in children
Causes of chronic cough in children
Croup: Clinical features, evaluation, and diagnosis
Emergency evaluation of acute upper airway obstruction in children
Common causes of hoarseness in children
Parainfluenza viruses in children
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
(www.healthychildren.org/English/health-issues/conditions/chest-lungs/pages/Croup.aspx)
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