How Long Is Croup Contagious?

By Sherry Baker @SherryNewsViews
December 08, 2023
How Long Is Croup Contagious?

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

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

A child with croup will have a barking cough, often compared to that of a dog or seal. Your child also might wheeze.

Viruses known as HPIV-1 and HPIV-2 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. 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. It is likely to be contagious not only while the child has obvious symptoms but also during the incubation period of the sickness, even before the cough and other symptoms begin.

The most contagious period is during the early stage of the illness, the CDC explains. In all, how long croup is contagious ranges 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. 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. The sound of stridor is almost a musical, whistling sound, occurring when your child inhales. It’s common even with mild croup and is more likely to occur if your child 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. Your child can let a hot shower produce steam in a bathroom with the door closed.

Keep the head of your child’s bed elevated. You can also 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.

How long does croup last if the viral infection is serious?

Although complications are not common, they do occur and sometimes lead to hospital stays.

Stridor while your child is at rest could be a warning of severe croup. Difficulty breathing may increase, and your child may stop drinking or eating. If your child’s airway swells more, breathing may be extremely difficult.

Don’t ignore severe symptoms of croup. 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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December 08, 2023

Reviewed By:  

Janet O’Dell, RN