Croup is a common respiratory tract infection in children. It tends to affect younger children the most because of their smaller airways and is typically seen at 6 months to 3 years of age. Croup is seen more often in the fall and early winter and is slightly more common in boys than girls.

Croup is usually caused by a virus. Less often, it can be caused by bacteria, allergies, or acid reflux from the stomach. The virus first infects the nose and throat, then spreads along the back of the throat to the larynx (voice box) and trachea (windpipe). This causes the larynx and trachea to swell, narrowing the airway, and leading to the characteristic barking cough and hoarseness associated with croup.


The early symptoms of croup can include a nonspecific cough, runny nose, and fever for about 24–72 hours, followed by an abrupt onset of barky cough, hoarse voice, and noisy breathing during the night. Croup can be very mild or very severe, depending on how difficult it is for the child to pull air into their lungs. Croup symptoms are typically worse at night. The severity of symptoms can change quickly depending on whether the child is calm or agitated. Agitation increases narrowing of the airway, leading to even more difficulty breathing and further agitation.

Usually, symptoms are short-lived. For the majority of children, the barky cough will go away on its own within 2 days. Croup is most often diagnosed based on the child’s symptoms, including a barking cough and noisy breathing. X-rays or other laboratory testing are rarely needed to make the diagnosis.

How it spreads

Croup is spread through direct contact with a person or fluids from another person who has the disease. Children with croup should be considered contagious for 3 days after the illness begins or until the fever is gone. Simple hygiene measures like frequent hand washing can help prevent infection with viruses that lead to croup.


Management of croup is based on the severity of the illness. Mild croup can usually be treated at home. You can use mist from a humidifier or sit with your child in a bathroom filled with steam generated by running hot water from the shower. Allowing your child to breathe cool air during the night by opening a window or door may also be helpful.

For moderate to severe croup, your doctor may prescribe a steroid medicine. This reduces swelling in the child’s airway and helps them to breathe more easily. The medication will not keep them from coughing but should help reduce the noisy breathing. Antibiotics are not effective against viruses, so they are not an appropriate form of treatment for croup. In severe cases, the child may need to have a breathing treatment in the hospital.

When to seek emergency care

If your child develops any symptoms of severe croup, seek medical attention immediately. Symptoms of severe croup include:

  • Difficulty breathing
  • Pale or blueish skin
  • Severe coughing spells
  • Drooling or difficulty swallowing
  • Inability to speak or cry due to difficulty taking a breath
  • A whistling sound or noisy, high-pitched breathing while sitting or resting
  • Sucking in of skin around the ribs with breathing
Categories: Infants, Influenza/Colds, Toddlers
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