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Last Updated on Jun 21, 2022
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What is Croup?

Croup is a respiratory infection that is most commonly seen in young children below the age of 6 years. The upper respiratory tract or airway is infected, swells up, and the child develops a cough that resembles the barking sound of a seal.


In children, the larynx (voice box) is small. The larynx passes through a cartilaginous ring. When the cartilaginous ring becomes swollen due to infection, it squeezes the larynx causing the air passage to narrow. The narrow passage results in hoarse and barking sounds in children. The accumulation of mucus in the area of infection is another factor that causes the air passage to become narrow. Croup affects the larynx, trachea, and the bronchi.

Croup - Respiratory Infection

Croup is a term that includes all conditions affecting the bronchi, larynx, and trachea (e.g. laryngotracheobronchopneumonitis, laryngotracheitis, laryngotracheobronchitis, spasmodic croup). The croup syndrome occurs more frequently in the winter and fall months. Croup is also the cause for numerous incidents of hospitalization in children under the age of 4 years.

What are the Causes of Croup?

There are different causes of croup yet only a small percentage of exposed individuals develop croup.

Viral infection is the main cause of croup. Nearly 75% of croup cases are caused by parainfluenza viruses (types 1, 2, 3). Laryngotracheobronchitis may be caused by other viruses, such as rhinoviruses, adenoviruses, syncytial viruses, influenza viruses A and B, as well as enteroviruses.

Main Cause of Croup - Viral infection

Spasmodic croup is not caused directly by an infection but is an indirect reaction to a viral infection.

Bacteria can cause laryngotracheobronchitis, and laryngotracheobronchopneumonitis. Some of the bacterial agents are Haemophilus influenzae, Corynebacterium diphtheriae, and Staphylococcus aureus.


Other causes of croup include:

  • Allergies (such as food allergies, pollen)
  • Acid reflux
  • Breathing in powder (flour, sugar) that irritates the air passage, or
  • Presence of foreign objects (e.g. seeds or nuts)

What Are The Symptoms and Signs of Croup?

The symptoms of croup may last from a few hours (spasmodic) to a whole week (viral). The symptoms initially begin with a common cold (fever, runny nose, and sore throat) and then progressively worsen. The symptoms are normally observed at night.

All the symptoms generally point to a discomfort in the upper respiratory tract. The characteristic symptoms are listed below:

Symptom of Croup - Hoarse Voice
  • High-pitched sound when breathing in (inspiratory stridor) and sometimes when exhaling (expiratory stridor)
  • Cough has a barking sound
  • Varying degrees of respiratory discomfort
  • The skin on the chest wall is drawn in during breathing while at rest
  • Fatigue
  • Dusky complexion due to lack of appropriate oxygen supply
  • Reduced state of alertness
  • Trouble with feeding and talking
  • Breathing difficulty (dyspnea)
  • Blue discoloration in the area around the mouth

How Do You Diagnose Croup?

On observing signs of barking cough and inspiratory stridor, the child is taken to the doctor who conducts a physical and medical examination. The doctor will recommend blood tests, neck and chest x-rays.

During the physical examination, the doctor will listen to the breath sounds within the chest, the difficulty in breathing, and wheezing.


Croup may be diagnosed with computed tomography and x-rays. Radiology however, does not always help in diagnosing croup. The characteristic feature of croup in an x-ray is the occurrence of a steeple sign that represents a narrow column of air that is passing through the narrowed airway.

X-Ray Helps in the Diagnosis of Croup

The throat x-ray might reveal evidence of narrowing or impaction of a foreign object. An inflamed epiglottis can also be revealed in a throat x-ray.

Pulse oximeter is a small sensor that is used to detect the level of oxygen in the blood. Those with spasmodic croup tend to have lower oxygen levels in the blood.

Laryngoscopy may be indicated when there is an issue with the voice and breathing, or numerous recurrences of croup to rule out other conditions causing obstruction.

Computed tomography appears to confirm the reason for the obstruction in the respiratory airway in ambiguous cases, such as stridor in babies less than 6 months of age.

How Do You Treat Croup?

The child should be kept calm and placed in a relaxed and reassuring atmosphere to minimize agitation, oxygen demand and respiratory muscle fatigue from crying.

Croup is routinely treated with steroids, epinephrine being given for severe cases. Oxygen therapy may be necessary if the oxygen saturation is less than 92%. In very severe cases, endotracheal intubation may be resorted to.

Corticosteroids: Steroid treatment has been shown to be effective in reducing the recurrence of croup. Dexamethasone is a commonly used oral steroid to treat croup that is mild to moderate in severity. Prednisolone is another steroid used for the same purpose. Adrenaline is given to reduce the spasms in the upper respiratory passage and aids the action of the steroid medications.

Corticosteroids Helps in the Treatment of Croup

Epinephrine: This is another standard treatment that is prescribed for croup. The duration of action is for approximately 2 hours. It reduces the inflammation in the trachea and larynx as well as the swelling of the mucosa. The high-pitched breathing sound is reduced within half an hour. One of the drawbacks is that following 2 hours, the symptoms could recur with increased vigor. So, when children are given epinephrine in the emergency care, they are made to stay for approximately 4 hours to confirm that all the symptoms have gone.


If oxygen administration becomes necessary, it is administered using a blow-by technique.

There is little evidence that mist therapy, considered a traditional form of treatment might help. Placing children in mist tents, a cold and wet environment and separating them from parents may actually provoke anxiety or agitation and is to be avoided.

How Do You Prevent Croup?

  • Good hygienic practices help to prevent croup since it is spread like the common cold. Hence, keeping the surroundings clean and washing hands can help to prevent the incidence of croup.
  • Vaccinations for infections such as diphtheria and Haemophilus influenzae, which can give rise to croup, are also effective in preventing croup. Till date there is no vaccine for prevention of Parainfluenza.

Health Tips

  • Make the child drink plenty of water in small quantities.
  • Medications are ineffective in treating croup as the condition will just go away on its own. However, paracetamol may be given to combat fever associated with the infection. No cold or cough medications are advised since they do not really cure croup and also induce side effects.
  • Do not use steam therapy as it can cause burns.
  • Remain calm to avoid unnecessary agitation in the child who is already scared of the symptoms. Read a book or distract the child with television to calm the child and ease the symptoms.
  • Facilitate ease in breathing by making the child sit upright in bed.
Medindia adheres to strict ethical publishing standards to provide accurate, relevant, and current health content. We source our material from reputable places such as peer-reviewed journals, academic institutions, research bodies, medical associations, and occasionally, non-profit organizations. We welcome and value audience feedback as a part of our commitment to health literacy and informed decision-making.
  1. Cherry JD. Croup. N Engl J Med. 2008;358:384-391.
  2. Knutson D, Aring A. Viral Croup. Am Fam Physician. 2004;69(3):535-540.
  3. Overview - Croup - (http://www.mayoclinic.org/diseases-conditions/croup/home/ovc-20166699)
  4. Croup - (https://medlineplus.gov/ency/article/000959.htm)
  5. How to Care for Your Child’s Croupy Cough - (https://health.clevelandclinic.org/2015/09/care-childs-croupy-cough/)
  6. What is croup? - (http://www.health.vic.gov.au/edfactsheets/downloads/croup.pdf)
  7. Know About Croup - (http://www.hopkinsmedicine.org/healthlibrary/conditions/pediatrics/croup_90,P02942)
  8. Introduction - Croup - (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2528757/)
  9. Croup - Laryngotracheobronchitis - (https://en.wikipedia.org/wiki/Croup#Diagnosis)

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