How Long Is Croup Contagious?

By Sherry Baker @SherryNewsViews
January 18, 2019
Thermometer in sick girl's mouth --- Image by © Patrick Lane Photography/Corbis

How long is croup contagious includes an incubation period of a few days and several days after symptoms develop. Learn how it spreads and how to treat it.

Croup is a co​mmon respiratory illness in young children that’s sometimes frightening for both kids and their parents. Symptoms include coughing, sneezing, respiratory secretions — and worrisome, loud, and distinctive coughing sounds.

So, what does croup sound like, exactly? It’s primarily a barking sound, often compared to that of a dog or even a seal. There can be wheezing, too.

Viruses known as HPIV-1 and HPIV-2 both cause croup, with HPIV-1 identified as the primary cause in children, according to the Centers for Disease Control and Prevention (CDC). Kids are most likely to catch croup between the ages of three months and five years of age. Although older children and adults can get croup, it’s uncommon because their windpipes are larger, and swelling is less likely to get in the way of breathing, according to the American Academy of Pediatrics.


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How long is croup contagious?

The virus that causes croup is very contagious and spreads, primarily between children, via airborne droplets from sneezing and coughing or indirectly from contact with toys, dishes, or other objects that have mucus droplets on them. That’s why frequent handwashing and washing of toys can help lower the odds of spreading the disease.

Just how long is croup contagious doesn’t have an exact answer. However, it is likely to be contagious not only while the child has obvious symptoms but also in the incubation period of the sickness — even before the cough and other symptoms begin.

However, the most contagious period is during the early stage of the illness, the CDC explains. In all, how long is croup contagious estimates range from three days to a week after the illness begins or until the fever is gone.

Pay attention to croup sounds and symptoms

Most kids with croup have a low fever, but temperatures can spike as high as 104, the American Academy of Pediatrics explains. In addition to causing fever and cold-type symptoms, the HPIV-1 virus triggers swelling of the larynx (often called the voice box) and windpipe (trachea). Over the course of a few days, the airway below the vocal cords becomes constricted, making breathing noisy and sometimes difficult. The croup bark-like cough usually worsens at night.

Sometimes croup also causes another sound called stridor. What does croup sound like if stridor develops? It’s almost a musical, whistling sound, occurring when your child inhales. It’s common even with mild croup and is more likely if the youngster is active or crying.

How to treat croup at home

A child with mild croup can be treated at home, the American Academy of Family Physicians points out. It’s important to provide more fluids than normal and, to help with breathing, keep air moist with a mist humidifier or by letting a hot shower produce steam in a bathroom with the door closed. Keep the head of the child’s bed elevated. Also helpful: Take a wet, warm washcloth and have your child breathe through it for a few minutes.

Sometimes the intense coughing of croup can cause chest pain. Do not give your child aspirin, however, which can cause complications. Instead, ask your doctor or pharmacist to recommend other over-the-counter pain medicines.

How long does croup last? Most cases are mild, with symptoms occurring primarily for three to five days — although it may take about a week for your child to feel completely well. A doctor may prescribe a steroid to decrease inflammation in the airways of a persistent case.

Look: Know when to call 911

How long does croup last if the viral infection is serious? Although complications are not common, they do occur and even rarely lead to hospital stays.

If you hear stridor while your child is at rest, that can be a warning of severe croup. Difficulty breathing may increase, and your child may stop drinking or eating. And if the airway swells more, breathing may be extremely difficult.

These symptoms should never be ignored — your child might not be getting enough oxygen into his or her blood. You may even notice a blueish tinge to your child’s fingernails, mouth, or nose.

While severe cases of croup don’t occur often, never hesitate if your child’s stridor is worsening. Call 911 or head immediately to an emergency room.


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March 26, 2020

Reviewed By:  

Janet O’Dell, RN