Croup is a viral infection of the upper airway that most often affects children between three months and five years of age.

The virus causes the voice box and windpipe to swell, which results in a characteristic bark-like cough. Croup is usually mild and lasts for three to five days; however, it can result in severe respiratory distress in some cases.

In this article, we will provide an overview of croup, including its symptoms, causes, and treatment.

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What is Croup?

Croup (laryngotracheobronchitis) is a viral infection of the upper airway that results in subglottic swelling and an obstruction below the vocal cords. It most commonly occurs in infants and children and results in inspiratory stridor and a barking cough.

Croup is typically caused by a viral infection, with the parainfluenza virus being the most common.

It can be contracted by breathing in respiratory droplets from an infected individual, or by touching contaminated surfaces and then touching the mouth or nose.

Signs and Symptoms:

Croups can range in severity from mild to severe. The most common symptoms include:

  • Barking cough
  • Hoarse voice
  • Inspiratory stridor
  • Difficulty breathing
  • Fever

The symptoms of croup typically last for three to five days; however, in some cases, they may last for up to two weeks.

In severe cases, croup can result in respiratory distress and airway obstruction. This can lead to increased work of breathing, retractions, and cyanosis.


The vast majority of cases of croup can be treated at home with simple measures, such as:

  • Humidifiers or steam inhalation
  • Cool-mist vaporizers
  • Oral fluids
  • Over-the-counter pain relievers

In severe cases, hospitalization may be necessary for observation and other treatment methods, including:

  • Intravenous fluids
  • Oxygen therapy
  • Aerosol medications
  • Corticosteroids

Intubation and mechanical ventilation may be indicated in severe cases. This involves inserting a breathing tube through the nose or mouth and connecting it to a machine for ventilatory support.

Croup Practice Questions:

1. What is croup?
Croup is a condition characterized by hoarseness, a resonant cough described as “barking” or “brassy”, varying degrees of inspiratory stridor, and varying degrees of respiratory distress resulting from swelling or obstruction in the region of the larynx and subglottic airway. Croup syndromes can affect the larynx, trachea, and bronchi. The important thing to remember is that the swelling is BELOW the glottis. 

2. What is another name for croup?

3. What is the description of acute laryngotracheobronchitis?
It is the most common croup syndrome with viral causing agents. The disease is usually preceded by URI. The inflammation of the mucosal lining in the larynx and trachea causes narrowing of the airway. This causes the child to struggle to inhale air past the obstruction and into the lungs producing the characteristic inspiratory stridor and suprasternal retractions.

4. What are the clinical manifestations of laryngotracheobronchitis?
Barking, seal-like, brassy cough, hoarseness, acute stridor, symptoms of hypoxia may become present, respiratory distress and signs of impending airway obstruction include increased pulse and respiratory rate, chest retractions, flaring nares, and increased restlessness.

5. What is the therapeutic management of laryngotracheobronchitis?
The major objective of medical management is maintaining the airway and providing adequate respiratory exchange. Application of humidity with cool mist provides some relief (mild cases). Severe cases of LTB use nebulizer epinephrine. Oral steroids are an effective treatment of croup. Intubation and ventilation may be required during severe airway obstruction.

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6. What is the most common cause of stridor?

7. What is the most common cause of stridor but is more severe than croup?

8. What are the signs and symptoms of croup?
Baby (6 months – 1.5 years) will have stridor, barking cough, hoarse voice, inspiratory stridor, trouble breathing (retractions, can see ribs) and then have a characteristic seal-like bark.

9. What is the most common cause of croup?
Parainfluenza 1, 2, 3 and could be any virus.

10. What is the sign of croup on an x-ray?
Steeple sign.

11. What is the most common age for getting croup?
6 months to 1.5 years and a maximum of 36 months.

12. What is the treatment for croup?
Treatment is basically the same for epiglottitis even though epiglottitis is a bacterial cause. For croup, it is a viral cause, so there is not much that can be done, just give nebulized cold or hot steam and monitor the airway and wait for it to resolve on its own. Keep child comfortable. Take into cool night air or breathe warm mist. If severe, administer Dexamethasone.

13. What is the pathophysiology for croup?
Often starts in the upper respiratory tract and progresses to larynx and trachea. Laryngotracheitis or laryngotracheobronchitis with inflammation of the larynx and trachea (LT) often can involve the bronchi (LTB) and no distinct clinical difference between LT and LTB.

14. What is inflammation and edema in the subglottic area?
Least distensible part of the airway (surrounded by cricoid) and narrow diameter impedes air flow leading to stridor and “seal bark” cough.

15. What is stridor?
High-pitched sound due to abnormal flow.

16. What are the clinical manifestations of croup?
Distinctive “brassy”, “barking”, “seal bark”, “rough and stridorouscough; may have stridor (high-pitched sound with breathing); many have prodromal upper respiratory signs and symptoms; and, generally, improve over 3-4 days.

17. What is the primary clinical diagnosis of croup?
“Steeple sign”: X-ray shows subglottic narrowing and airway appears as a steeple.

18. What are the medications for croup?
Steroids indicated for all regardless of severity because it lessens severity and duration of signs and symptoms. Give IM dexamethasone in single dose: 0.6 mg/kg; oral dexamethasone in single dose: 0.15 mg/kg for mild to moderate; and, inhaled budesonide (2-4 mg). For moderate to severe croup, nebulized racemic or L-epinephrine (0.05 mL/kg of 2.25% solution) and observe for 3 hours after a dose for rebound distress. No antibiotics unless bacterial infection is present.

19. What is the description of croup syndrome?
Croup is a group of symptoms that are characterized by hoarseness, barking or brassing cough “croupy cough”, inspiratory stridor, various degrees of respiratory distress as a result of swelling and inflammation in the larynx. It affects larynx, trachea and bronchi. The symptoms are the same with acute epiglottitis, acute laryngitis, acute laryngotracheobronchitis, acute spasmotic laryngitis and acute trancheitis.

20. Why is croup syndrome more susceptible to infants and children?
Infant and small children are more susceptible to this disease because their airways are smaller.

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21. How is croup described?
When there is inflammation, it is easily obstructed because of their small airways. When there is edema, the airway will be smaller. When patients have croup there is narrowing and edema. Air is trying to squeeze out through the narrow airway.

22. What can be seen in croup?
Narrowing and edema in the airway BELOW the glottis. 

23. What is one of the most common types of croup?
Acute laryngotracheobronchitis.

24. What age does acute laryngotracheobronchitis affect children?
Less than 5 years old.

25. What is the cause of acute laryngotracheobronchitis?
RSV, influenza type A & B, parainfluenza types 3 & 2, measles, and mycoplasma pneumoniae.

26. What is the onset of acute laryngotracheobronchitis?
Gradual onset of low-grade fever.

27. What are the signs and symptoms of acute laryngotracheobronchitis?
Children have upper respiratory infection first, worse at night, crying and agitation makes it worse, inspiratory stridor (narrowing of airway), brassy cough, hoarseness, dyspnea, restlessness, irritability, fever, as airway narrows, it makes it harder for the child to exhale, respiratory distress infants and young children exhibit, and intercostal retractions, nasal flaring, tachypnea, stridor.

28. What happens to the airways in acute laryngotracheobronchitis?
It narrows and makes it hard for the child to breathe.

29. What do infants and young children exhibit in acute laryngotracheobronchitis?
Intercostal retractions, nasal flaring, tachypnea, and stridor.

30. What are the treatments for acute laryngotracheobronchitis?
Humidity, nebulized epinephrine, and anti-inflammatory (to reduce the subglottic edema that is present).

31. When does croup typically occur?
Most likely occur overnight from 10 pm to 4 am or early morning 7 am to 11 am.

32. What is the most common cause of croup?
Parainfluenza virus type 1.

33. How does the virus infect the nasal and pharyngeal mucosal epithelium?
It spreads along respiratory epithelium to the larynx and trachea.

34. What happens in severe cases of croup?
Mucosal edema, fibrinous exudates, and pseudomembranes can build up on the tracheal surface and further contribute to airway narrowing.

35. Does croup affect the  subglottic or supraglottis region?
Subglottic and narrowing of the trachea in the “sub” glottic area.

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36. What are the clinical features of croup?
Gradual onset and initially present with URI symptoms (coryza, congestion).

37. What are the progressions of the disease over 12‐48 hours?
Fever, hoarseness, barking cough (expiratory) and stridor (inspiratory).

38. What are the croup physical exam findings?
Hoarseness, nasal mucosa congested, mild to no pharyngeal erythema, mild tachypnea, prolonged inspiratory phase, stridor (inspiratory) and rales if have LTB.

39. What are the severe croup physical exam findings?
Suprasternal, subcostal, intercostal retractions, decreased breath sounds, hypoxia and cyanosis.

40. What are the factors associated with severe croup?
Sudden onset of symptoms, rapid progression (<12 hours), previous episodes of croup, abnormality of the airway and medical conditions predispose to respiratory failure (neuromuscular disorders, asthma, cystic fibrosis).

41. What is the hallmark chest x-ray finding with croup?
Steeple sign.

42. What are the complications of croup?
Hypoxemia, respiratory failure, pulmonary edema, pneumothorax, secondary bacterial infection, tracheitis, bronchopneumonia, and pneumonia.

43. What is the management of croup?
It depends on the result of the severity assessment and phone triage. For mild croup, home treatment, mist, antipyretics, encourage fluid intake, steam, exposure to cold air and follow up phone call. For outpatient treatment, dexamethasone in single oral dose. For moderate to severe croup, evaluated in the ED or office, administration of humidified air/oxygen, avoid exacerbating anxiety, as will worsen symptoms, Dexamethasone po, IM or IV (single dose), nebulized racemic epinephrine Q15‐20 mins prn, continuously monitor pulse oxygen and respiratory status, IV fluids dehydrated and intubation (1% of cases). Observe for 3‐4 hours before discharge.

44. What are the manifestations of moderate to severe croup that needs to be hospitalized?
Worsens or fails to improve with dexamethasone and epinephrine; have retractions; need supplemental oxygen; poor by mouth intake; toxic in appearance; cardiac monitoring; nebulized epinephrine; and, repeat dexamethasone.

45. What are the signs and symptoms associated with respiratory infection in infants and small children?
Fever, poor feeding/anorexia, vomiting, diarrhea, abdominal pain, nasal blockage, nasal discharge, cough, respiratory sound, sore throat and meningismus.

46. What are the types of URI’s in children?
Acute nasopharyngitis (common cold) caused by numerous viruses such as RSV, rhinovirus, adenovirus, influenza, and parainfluenza viruses. Fever varies with the child’s age. Older children have low-grade fevers. Symptoms can last up to 10 days and home management varies with age.

47. What care is given in children with respiratory infection?
Assessment of respiratory status, monitor oxygen saturation, suction infant with bulb syringe or nasal aspirator, use NS nose gtts before suctioning, may be placed NPO to avoid risk of aspiration, avoid milk, keep well hydrated, prevent spread of infection, bedside humidifier, and Tylenol or Advil for fever. AAP recommends over the counter cough and cold medicines not be given to children under 6 years of age because of risk of life-threatening side effects and questionable efficacy.

48. How does croup begin?
As an upper respiratory infection with nasal congestion and cough.

49. What area does croup affect and how?
Larynx and subglottic area and they become inflamed leading to obstruction, swelling and exudate.

50. What infection does croup lead to?


What is Laryngotracheobronchitis?

Laryngotracheobronchitis is the medical term for croup. It’s a viral infection of the upper airway that results in subglottic swelling and an obstruction below the vocal cords.

This virus is most commonly seen in children and results in symptoms such as a barking cough, hoarse voice, and difficulty breathing.

What is a Croup Tent?

A croup tent is a device that can be used to deliver aerosolized medication to a child with croup. It consists of a collapsible tent made of thin plastic that is placed over the child’s bed.

An aerosol medication is nebulized and delivered through a tube into the tent, where the child can inhale it for therapeutic purposes. This method of delivery is effective in treating croup by reducing the inflammation in the airway.

What is the Difference Between Croup and Whooping Cough?

Croup and whooping cough are both respiratory infections that can cause severe symptoms in children. However, there are some key differences between the two.

Whooping cough is a bacterial infection that is more serious and can last for weeks or months, while croup is a viral infection that typically lasts for three to five days.

Whooping cough can also be more severe and can lead to pneumonia, while croup is typically a milder illness.

What Does a Croup Cough Sound Like?

A croup cough is often described as sounding like a “seal bark.” It is a harsh, dry cough that is caused by inflammation of the upper airway.

This inflammation results in the narrowing of the airway, which leads to the characteristic barking sound of a croup cough.

Final Thoughts

Croup is a viral infection of the upper airway that most often affects infants and young children. It is typically mild and resolves on its own within a few days. However, in some cases, it can be severe and lead to respiratory distress.

If you found this information useful, we have a similar guide on epiglottitis that I think you will enjoy. Thanks for reading!

Medical Disclaimer: This content is for educational and informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Please consult with a physician with any questions that you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you read in this article. We strive for 100% accuracy, but errors may occur, and medications, protocols, and treatment methods may change over time.


The following are the sources that were used while doing research for this article:

  • Rrt, Des Terry Jardins MEd, and Burton George Md Facp Fccp Faarc. Clinical Manifestations and Assessment of Respiratory Disease. 8th ed., Mosby, 2019.
  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
  • Jardins, Des Terry. Cardiopulmonary Anatomy & Physiology: Essentials of Respiratory Care. 7th ed., Cengage Learning, 2019.
  • Smith, Dustin. “Croup: Diagnosis and Management.” PubMed, 1 May 2018,
  • “Laryngotracheobronchitis.” National Center for Biotechnology Information, U.S. National Library of Medicine, 2 July 2020,

Medical Disclaimer: The information provided by Respiratory Therapy Zone is for educational and informational purposes only. It should not be used as a substitute for professional medical advice, diagnosis, or treatment. Please consult with a physician with any questions that you may have regarding a medical condition.