Is Croup Contagious?

Medically Reviewed on 7/28/2022

What is croup?

Croup is very contagious. It is spread by airborne droplets usually from an infected child to another child or adult.

Croup is an infectious inflammation of the larynx and trachea usually in children. Croup typically interferes with breathing and causes a barking cough. The individual may be without fever or have a low-grade fever. Viruses typically cause the inflammation of the larynx (voice box and vocal cords), trachea (windpipe), and/or bronchi that is characteristic of croup.

Common viruses involved include parainfluenza types 1, 2, 3, adenovirus, and respiratory syncytial virus (or RSV) although many other viral types may also cause croup; even a bacterium, Mycoplasma pneumoniae, may occasionally cause the disease. Croup occurs mainly in children 6 months to 3 years of age, although older children and adults can be infected.

Another type of croup is spasmodic croup. Spasmodic croup is almost identical to croup, but an allergic reaction causes it. Spasmodic croup occurs less frequently than "croup" and has the same features, except it is not contagious.

Is croup contagious?

Croup is very contagious. Airborne droplets spread from an infected child to another child or adult.

Croup viruses can be transferred to pregnant women, but the viruses that cause croup should not affect the fetus. However, pregnant women may have more severe symptoms of croup than non-pregnant women.

How is croup transmitted?

Croup is a very common ailment in children (average age is about 2 years old) and is considered to be highly contagious to other children. The viruses that cause croup are easily spread through the air by mucus droplets during sneezing or coughing, through direct person-to-person contact, as well as by indirect contact when items such as toys, utensils, cups, and other objects have contaminated mucus on them from an infected child.

How long is croup contagious?

Croup may be contagious during the incubation period and for about seven to 10 days after symptoms develop.


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What is the incubation period for croup?

The incubation period for croup is relatively short. After exposure to the virus, symptoms of croup usually develop for two to three days that may extend to seven days after exposure to viruses that cause the disease.

How will someone know if he or she is infected with croup?

  • Croup causes a cough that sounds like a bark of a seal or a dog.
  • Children with croup often have some trouble breathing because the airway is narrowed in this disease and breathing produces a sound (stridor) as air passes back and forth.
  • Fortunately, many children (and adults) who get croup have very mild symptoms, and the disease resembles more of a bad cold with congestion.
  • Croup is usually diagnosed simply by the doctor listening for the barking cough and stridor.
  • However, sometimes other conditions can lead to similar symptoms, and occasionally a physician will order an X-ray of the child's neck to determine airway narrowing (steeple or pencil sign).

What is the best thing to do for croup?

Care of a child with croup involves decreasing the child's symptoms. Croup symptoms usually last for about three to seven days with the most severe symptoms on days two and three. Gradually, the symptoms abate, and the child is usually cured of the disease in about a week; some patients exhibit symptoms for two weeks.

Treatment of croup involves corticosteroids and nebulized epinephrine; antibiotics are not usually prescribed because croup infection is viral.

When should someone seek medical care for croup?

Although many individuals with croup can be effectively cared for at home, the following list of symptoms suggests that a child should be seen emergently if these symptoms develop:

  • Difficult, labored, or very rapid breathing
  • Bluish or pale coloration around the mouth
  • Loud stridor
  • Difficulty swallowing
  • Increasing or excessive drooling
  • Dehydration (decreased urination, few or no tears, dry mouth, sunken eyes)
  • A fatigued and/or sick appearance
Medically Reviewed on 7/28/2022
American Academy of Pediatrics. "Croup and Your Young Child." Nov. 21, 2015. <>.