Reviewed on 11/21/2022

Things to Know About Croup

Signs of Croup in a Child
Picture of Croup by CNRI/Photo Researchers Inc, Steve Pomberg/WebMD

Croup is caused by an acute viral infection of the upper respiratory tract. It is also called laryngotracheobronchitis since it affects the larynx, trachea, and bronchi. This infection results in inflammation increased mucus production and swelling of the upper airways. Although croup usually resolves on its own, some children with croup will require admission to the hospital. Croup continues to be one of the most common causes of respiratory distress in young children.

  • Children between the ages of 6 months and 3 years of age are most likely to get croup. This common viral illness is estimated to occur annually in 5% of children between the ages of 6 months and 3 years and is the most common cause of stridor (upper airway wheezing during inspiration) in this age group.
  • Croup is rarely seen in adults because their larger breathing passages (trachea and larynx) can accommodate the inflammation without producing symptoms.
  • Some children appear to be particularly prone to croup and have a number of infections.
  • Boys are more prone than girls, with peak seasonal outbreaks in late fall and winter.
  • Croup should be differentiated from more serious medical diagnoses, including acute epiglottitis, bacterial tracheitis, severe allergic reactions, or an inhaled foreign body.
  • Croup is very contagious
  • Croup causes a cough that sounds like barking.

What Causes Croup?

Croup is most commonly caused by a viral respiratory infection that is easily passed among children. Common viral causes include

  • parainfluenza (responsible for the majority of infections),
  • influenza,
  • adenovirus,
  • respiratory syncytial virus (RSV), and
  • rhinovirus.

Prior to the vaccine era, diphtheria caused most cases of croup and was referred to as membranous croup, but today, fortunately, vaccination against diphtheria has made it an exceedingly rare disease.

What Are the Symptoms of Croup?

  • The infection starts with a cold, cough, and low-grade temperature lasting two to three days.
  • Then the typical barking cough (sounds like a seal) is usually present by day three and is more likely to be worse at night.
  • The presence of stridor (wheezing on inspiration), hoarseness, difficulty swallowing, and respiratory distress are common but may or may not be severe.

When Should I Call the Doctor About Croup?

Call your doctor if the following conditions develop:

  • Your child has a high fever.
  • The child is breathing faster than normal or has noisy breathing.
  • The child has signs of dehydration, including increased sleepiness, dry mouth, or decreased urination.
  • The child starts having loud, high-pitched wheezing while breathing.
  • The child begins to struggle to breathe or speak in short sentences because of a lack of breath.
  • The child has difficulty swallowing or is drooling excessively.
  • The child is having signs of restlessness or sluggishness either from respiratory distress or dehydration.
  • The child has signs of respiratory distress, including retractions of skin around the ribs from deep breathing, nostril flaring, or rapid breathing; these symptoms suggest a medical emergency.

Cyanosis, which is a bluish color to the skin, lips, or nail bed, indicates a severe lack of oxygen in the body and should be considered an emergency, and 911 should be called.

How Is Croup Diagnosed?

The great majority of children with croup can be diagnosed from the history of the present illness and a physical examination that show the croup symptoms described above. Studies are not routinely required and should be reserved for those children who present with atypical symptoms or with extremely severe symptoms that are not obviously associated with croup. However, an anteroposterior neck X-ray may show a steeple or pencil sign indicating narrowing of the trachea.

  • A pulse oximeter may be used to determine if the child is getting an adequate amount of oxygen. This is a skin sensor, placed on the finger, toe, or ear, and connected to an oximeter machine by a wire. Normal levels would be above 95% on room air.
  • X-rays of the neck may be ordered to differentiate croup from epiglottitis, which is a more serious condition. Children with croup typically have visible upper airway narrowing, called a steeple sign that can be seen on X-rays.
  • Blood tests are usually not necessary.
  • Viral cultures and antibody tests are not recommended.

What Is the Treatment for Croup?

  • Overall, the initial goal is to determine the severity of the illness. This will guide the medical treatment. Although in the past, humidified oxygen or cool mist treatments were routinely recommended, studies have not proven these treatments to be effective.
  • Steroid therapy has been shown to be of benefit in all children with croup. It may be given orally, by injection, or by IV. Inhaled steroids appear to have limited value. Because most croup is caused by viral infections, antibiotics have not been shown to be beneficial in the treatment of croup.
  • Nebulized epinephrine or racemic epinephrine may be administered to children with moderate or severe symptoms. Currently, there is no evidence to support the use of racemic epinephrine over nebulized epinephrine.
  • If your child responds to treatment, the doctor may elect to observe the child for an additional few hours to make sure the symptoms do not return after the medications have worn off. If your child remains symptomatic after therapy, then the child will require admission to the hospital.

What Are the Home Remedies for Croup?

  • Although mist or humidified air and exposure to cold air have not been proven effective in treating the symptoms associated with croup, they are still routinely recommended by physicians since they are generally not invasive and have been described anecdotally as helping some children with moderate symptoms.
  • Consider substituting water or juice for milk products. Frequent sips of clear liquids can loosen mucus and prevent dehydration, which often occurs with croup.
  • Crying can trigger spasmodic coughing. Attempt to comfort your child to prevent agitation.
  • Acetaminophen (Children's Tylenol) or ibuprofen (Advil, Motrin) may be given for fever or sore throat. Aspirin-containing medications should never be given to children unless prescribed by a physician due to the risk of a serious liver condition called Reye's syndrome.
  • Over-the-counter cough medications are not recommended. Avoid exposure to respiratory irritants such as smoke.

What Is the Follow-up for Croup?

  • Have the child rest as much as possible.
  • Give him or her plenty of fluids to drink.
  • Keep your child calm, because breathing symptoms can worsen with crying and agitation.
  • Make certain your child takes his or her medications for the length of time prescribed, even if the child has improved.
  • If symptoms return or worsen, then notify your doctor or return to the emergency department.

How Can You Prevent Croup?

Croup is a contagious disease. If possible, avoid contact with others who have colds or cough symptoms.

  • Have children wash their hands often to reduce the chance of spreading the infection.
  • Get prompt treatment for symptoms of respiratory infection.
  • Increase the amount of fluids children drink.
  • Avoid exposure to respiratory irritants such as smoke.

What Is the Prognosis for Croup?

Although most children with croup improve after 48 hours, there are some cases that will take longer to resolve. In a small number of cases, admission to a hospital for more intensive management may be required. Of those admitted, only 1%-2% will be severe enough to require a breathing tube with mechanical ventilation or pediatric intensive care.

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Reviewed on 11/21/2022
Medically reviewed by Margaret Walsh, MD; American Board of Pediatrics

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Zoorob, R., M. Sidani, and J. Murray. "Croup: An Overview." Am Fam Physician 83.9 May 1, 2011: 1067-1073.