Croup is a short-lasting infectious childhood illness of the upper respiratory system, involving the upper airways of the lungs (bronchial tubes), vocal cords (larynx), and windpipe (trachea). Croup is most likely to occur in late autumn and early winter.
Croup most commonly occurs in children between six months and three years of age. It rarely occurs in children aged over six years.
Croup is contagious, especially during the first few days of illness. It is mainly spread by airborne infectious droplets sneezed or coughed by infected children. It can also be spread via infected mucus on surfaces and objects such as toys.
Most cases of croup are mild. Nevertheless, children with croup can become seriously ill so it is important to monitor their symptoms.
CausesCroup is usually caused by a viral infection. Many different viruses can be responsible for croup, including common cold and influenza (flu) viruses. Very rarely, croup may be caused by a bacterial infection. Many children who are infected with viruses that cause croup will not get croup but will develop symptoms of a cold.
Signs and symptoms
The differentiating symptom of croup is a cough that sounds like a barking seal and a harsh raspy noise when breathing in (called stridor). These symptoms are due to swelling of the vocal cords and windpipe resulting in narrowing of the airway, which makes breathing difficult.
These distinctive symptoms are preceded by fever, mild hoarseness and sore throat, and other cold-like symptoms.
Children have small airways and hence are more susceptible to having more marked symptoms with croup, especially children aged less than three years old.
Symptoms usually appear at night or become worse at night.
Spasmodic croup is a type of croup that causes coughing spasms (continuous coughing) that occur during the night and early morning. A barky cough and stridor is heard during the spasms. The spasms usually do not occur during the day and your child may seem better in terms of their breathing and hoarseness during the day.
The major concern in croup is progressive breathing difficulty as the air passages narrow. Close monitoring for breathing difficulties is important during the early stages of the illness, especially at night. Signs and symptoms of serious breathing problems include:
- Struggling to breath (worse than the noisy breathing)
- Excessive drooling or difficulty swallowing
- Bluish discolouration of the skin or lips (cyanosis)
- Sucking in of the chest, and rapid breathing
- Makes noisy, high-pitched breathing sounds (stridor) both when inhaling and exhaling
Although only a small percentage of children develop breathing difficulties serious enough to require hospitalisation, you should take your child to the nearest emergency department of dial 111 immediately if these signs are observed.
Croup is diagnosed by a doctor observing a child’s breathing, listening to their chest using a stethoscope, and examining their throat. X-rays and other tests may be required to exclude other illnesses.
Self-care measures at home are usually sufficient to treat the majority of cases of croup. Medical treatment is rarely required. Croup usually resolves on its own within three to six days.
Croup can be alarming for a child; hence comfort and reassurance is an important part of treatment.
Cool moist air may reduce vocal cord swelling and help breathing. This can be achieved by using a cool mist humidifier or sitting near an open window (while ensuring that your child is warmly clothed). Holding your child in an upright position may also make breathing easier for them. Do not let anyone smoke around your child.
Paracetamol and ibuprofen are helpful for pain relief and fever. However, aspirin should be avoided in the treatment of croup and other viral illnesses in children due to the possible association of aspirin with Reye’s syndrome, which is a serious illness causing liver and brain swelling.
Use of decongestants, cough and cold medications available from your pharmacy are not usually recommend because they are ineffective in children and can cause unwanted adverse effects.
Fluid intake is encouraged to avoid dehydration.
If symptoms continue beyond three to five days or worsen your doctor may prescribe a corticosteroid (e.g. dexamethasone) to reduce inflammation in the airways. Epinephrine is also effective in reducing airway inflammation but its effects are not long-lasting.
Antibiotics are rarely used because they are ineffective against viruses, which are the most common cause of croup. Antibiotics are reserved for those rare occasions when a bacterial infection causes croup or occurs at the same time as croup.
Because croup is most contagious during the first few days of fever and illness, infants and children should be kept at home and away from other children and adults until their temperature returns to normal and they feel better.
Frequent hand-washing is important to prevent spreading or contracting the infection. Avoiding close contact with people who have a respiratory infection.
Getting your child vaccinated for diphtheria, Haemophilus influenza (Hib), and measles can protect children from some of the most dangerous forms of croup.
Further information and support
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Mayo Clinic (2015). Croup (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/croup/symptoms-causes/syc-20350348 [Accessed: 07/05/18]
Ministry of Health (2017). Croup (Web Page). Wellington: New Zealand Government Ministry of Health. https://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/croup [Accessed: 07/05/18]
O’Toole, M.T. (Ed.) (2013). Croup. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis, MI: Elsevier Mosby.
Updated May 2018