Croup is an infection of the respiratory tract characterized by inspiratory stridor, cough, and hoarseness due to inflammation in the larynx and subglottic airway. A barking cough is the hallmark of croup among infants and young children, whereas hoarseness predominates in older children and adults.

Croup is a mild condition and resolves on its own with medications. But in some patients may cause significant upper airway obstruction and respiratory distress, and rarely death can occur. Croup affects about 15% of children, most commonly occurring in children 6 to 36 months of age. It is more common in boys, with a male: female ratio of about 4:1. More commonly occurs in early winter. An individual with a family history of croup is at risk.

Croup has been used to describe a variety of upper respiratory conditions in children including Laryngitis, Laryngotracheitis, Laryngotracheobronchitis, bacterial tracheitis, or spasmodic croup. Croup is usually caused by viruses and bacterial infection may occur secondarily. Most children with croup present with mild symptoms only in severe cases do the child present with stridor along with the cough.

Croup is diagnosed mainly based on the characteristic symptoms presented by the child. Laboratory investigations may be required rarely to confirm this diagnosis. Pulse oximetry is helpful to assess the need for supplemental oxygen support and to monitor for worsening respiratory infection. Most of the children get well completely within 7 days without requiring any treatment in severe cases corticosteroids and nebulized epinephrine is required. Some of the measures can reduce acquiring croup to a certain extent.

Croup: Causes

Croup is caused mainly caused by viruses and bacterial infection may occur secondarily.

The following are the important causes of developing croup −

  • Parainfluenza virus types 1, 2, and 3 are responsible for most of the croup cases contributing almost 80%. Type3 parainfluenza virus causes bronchiolitis and pneumonia in young infants and children. Parainfluenza types 1 and 2, account for nearly 66% of cases.

  • Other viruses such as Adenovirus, Respiratory syncytial virus (RSV), Enterovirus, Metapneumovirus, Reovirus, Influenza A and B, Human bocavirus, Coronavirus, Rhinovirus, Echovirus.

  • Rarer viruses such as Measles virus, herpes simplex virus, and varicella are also known to cause this.

  • The most common secondary bacterial pathogens include Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus.

Croup: Symptoms

The patient with croup mainly presents with the following symptoms that include −

  • A child with croup usually begins with nonspecific respiratory symptoms such as a running nose, sore throat, and cough.

  • Within 1-2 days, the characteristic signs of hoarseness, barking cough, and inspiratory stridor develop, often suddenly, along with a variable degree of respiratory distress. The symptoms usually worsen at the night, mostly between 10 pm and 4 am.

  • In most children, Symptoms typically resolve within 3-7 days but can last as long as 2 weeks

  • Fever is generally low-grade but can exceed 40°C in some children

  • In severe cases, the children present with audible stridor at rest and clinical evidence of respiratory distress. Some may have stridor only upon activity or agitation. Most children have no more than a "croupy" cough and hoarse cry. The respiratory arrest may occur suddenly during an episode of severe coughing

  • Warning symptoms in children with severe croup include increased respiratory and heart rate out of proportion to fever, hypotonia, unable to maintain adequate oral intake, and bluish discoloration of the body or extremities(cyanosis)

  • Severity assessment is done by various scores such as the Westley score depending on the presentation of the child’s symptoms

Croup: Risk Factors

Several factors play an important role in the development of claudication which includes −

  • Children between 6 months to 3 years of age are at increased risk

  • More common in the winter season

  • Children with a family history of croup

  • Children with a history of allergies and asthma

  • Children who are exposed to other children with respiratory infections, such as colds or the flu, may be more likely to develop croup.

  • Exposure to irritants such as tobacco smoke or other irritants

  • Children who live in crowded conditions, such as day-care centers, are at risk

Croup: Diagnosis

The diagnosis of the croup is mainly done based on history and some of the tests may be required for confirmation and to rule out underlying causes that include −

  • The child with croup presents characteristic symptoms based on which the diagnosis can be made.

  • A complete blood test shows an elevated white blood cell count

  • Imaging tests like X-ray are advised to rule out other causes of stridor such as soft tissue densities in the trachea, a retropharyngeal abscess, and epiglottitis. Chest radiographs may show a subglottic narrowing in 50% of children with croup, but this can also be seen in normal patients.

  • Pulse oximetry determines the percentage of oxyhemoglobin in blood pulsating through a network of capillaries. A low reading of oxygen saturation on pulse oximetry indicates significant respiratory impairment.

  • Direct or indirect laryngoscopy is not usually required and is indicated if there is a concern for an anatomical malformation of the upper airway, possible aspiration of a foreign object, or should the child rapidly deteriorate or not respond to routine therapy in an anticipated manner.

Conservative Treatment

The treatment is based on the severity of the symptoms. Croup is treated conservatively without the requirement of any surgeries.

Conservative treatment includes −

  • Croup caused by viruses is usually a self-limited disease that resolves within 3 days on its own but in some patients may last for up to seven days. Less than 5 percent of children with croup require hospital admission.

  • Antipyretics should be given to treat the fever

  • Vaporizer or steamer should be advised

  • The child should be advised to take plenty of fluids and use humidified air

  • A single dose of oral dexamethasone (0.6 mg/kg) in children with mild croup is given

  • In moderate to severe croup treatment involves Supportive care, Humidified air or humidified oxygen, monitoring of vitals, Fluids, and Intubation may be required in some children.

  • Corticosteroids nebulized epinephrine help to reduce the severity and shorten the course of the symptoms.

  • Antibiotics should be used if there are any specific bacterial complications of croup.

Croup: Prevention

Some of the measures that can help to prevent croup include −

  • A child with allergies and asthma should be adequately treated

  • The children in the home should be kept away from other children who have colds or the flu, especially during winter months when croup is more common

  • Using a cool mist humidifier in the child's bedroom during the winter season helps to keep the airways moist

  • Hygienic practices like washing hands frequently, and covering the mouth and nose while coughing or sneezing.

  • Avoid exposing the child to tobacco smoke or other irritants that can irritate their airways.

  • The child should receive all the recommended vaccinations


Croup is an upper respiratory tract infection mainly caused by viruses presenting with characteristic symptoms such as barking croup, hoarseness, and low-grade fever. Stridor is present in severe cases. Parainfluenza virus type 1, 2, and 3 is the main virus known to cause this.

No clinical investigations are required to diagnose the condition the characteristic symptoms help in diagnosing the condition. In some children, investigations may be required to rule out other causes. croup is a self-limiting disease that resolves within 3 to 7 days. Very rarely the child can get serious and needs hospitalization. In severe cases, corticosteroids and epinephrine are required. Some of the measures can prevent acquiring the croup to a certain extent.

Dr. Durgesh Kumar Sinha
Dr. Durgesh Kumar Sinha


Updated on: 17-Apr-2023


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