How Long Are You Contagious With Croup?
Key takeaways:
Croup is a respiratory illness that causes inflammation in your airways. Common cold viruses, the flu, and COVID-19 can all cause croup.
People are most contagious during the first 3 days of their croup illness.
After 3 days, it’s safe to go back to day care, school, or work as long as your symptoms are getting better and you no longer have a fever.
Croup, also known as laryngotracheobronchitis, is a common respiratory illness that people get in the fall and winter. It causes inflammation in the windpipe and voice box. Croup leads to symptoms such as a loud, barky cough and, sometimes, trouble breathing.
Common cold viruses, the flu, and COVID-19 can all cause croup. While babies and young children are more likely to get croup, adults can get it too.
If you or your child has croup symptoms, here’s what you need to know about how long you’re contagious and when it’s safe to get back to work, day care, and school.
How long is croup contagious?
Croup itself isn’t contagious. But the viruses that cause it, including COVID, are very contagious.
Experts estimate that you’re more likely to spread these viruses during the first 3 days of your illness.
People can usually go back to day care, school, or work after 3 days, as long as their symptoms are getting better and you no longer have a fever.
Not sure if it’s croup or just a cough? Here’s how to tell if your child has croup.
Croup is more common in kids. But adults can get croup too.
Looking for a natural cough remedy? Here’s a recipe for homemade cough syrup — it’s safe for both kids and adults.
It’s normal for cough and other symptoms, like a runny nose, to linger for up to 10 days. But when the fever is gone and you’re getting better, it’s safe to get back to your usual routine.
What’s the incubation period for croup?
In general, symptoms of croup develop 2 to 6 days after exposure to the viruses that cause it. This is called an incubation period. If you haven’t developed any symptoms after a week, you probably won’t get sick.
How does croup spread?
Viruses that can cause croup include:
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One thing these viruses have in common is that they spread from person to person through respiratory droplets. So, you can spread croup through actions like:
Coughing
Sneezing
Talking
Kissing
Sharing utensils or cups
You’re more likely to come down with croup if you come into contact with someone who’s sick with a virus that causes it.
How do you prevent croup from spreading?
Viruses that cause croup are very contagious. But you can keep yourself and your household members from getting sick or spreading the illness by taking these steps.
Wash your hands
Frequent handwashing gets germs off your hands and helps keep them out of your body. Wash with soap and water for 20 seconds. Or you can use an alcohol-based hand sanitizer if soap isn’t available.
Cover coughs and sneezes
Cough or sneeze into your elbow or a tissue, then wash your hands. This can be tough for young children. But with practice, even older toddlers can learn to do it.
Don’t touch your face
Croup viruses enter the body through your eyes, nose, and mouth. Keeping your hands away from your face lowers the risk of viruses getting from your hands and into your body.
Avoid people who are sick
Keep your distance from anyone with cold symptoms. If you’re sick, stay home to avoid spreading viruses to others.
Clean high-contact surfaces
Try to clean surfaces at home that you touch a lot — like doorknobs and stair rails. Some croup-causing viruses can live on surfaces for hours. Frequent cleaning lowers your risk of picking up these germs.
Get immunized
Get immunized against viruses that can cause croup. There’s no vaccine against the common cold. But there are flu shots and COVID vaccines that can keep you from getting sick with these viruses.
How do you treat croup?
There’s no cure for croup. But croup symptoms can usually be relieved using home remedies like:
Sitting in a steamy bathroom
Breathing in cold night air (be sure to dress children in warm clothing first)
Running a cool-mist vaporizer
While researchers haven’t found evidence that these measures work for everyone, they are safe to try and may help you or your child feel better.
If you or your child develops trouble breathing or noisy breathing (stridor), it’s time to see a healthcare professional. These are signs of serious croup.
People with more serious symptoms need treatment with prescription medications, like:
Dexamethasone (Decadron): A steroid that relieves airway inflammation within a few hours. Its effects last for 1 to 2 days — long enough for the worst croup symptoms to go away.
Epinephrine (Vaponephrine): A nebulized medication that provides temporary relief from inflammation. This makes it easier to breathe.
Frequently asked questions
Croup itself isn’t contagious. But you can pass the viruses that cause it to others for up to 6 days after you first get sick. You’re most contagious during the first 3 days of your illness.
Yes, adults can catch the viruses that cause croup from kids. While adults may not develop croup from these viruses, they can still develop other illnesses like upper respiratory tract infections or bronchitis.
Children should stay home from school or daycare until their croup symptoms are getting better and they are fever-free for 24 hours. It’s also a good idea to keep children away from people who are more vulnerable to viral illnesses like babies, older adults, and those with weakened immune systems.
The bottom line
Croup is a respiratory illness that causes inflammation in your windpipe and voice box. It’s caused by common cold viruses, the flu, and COVID. People who develop croup are most contagious during the first 3 days of their illness. But they can remain contagious for up to 6 days. After 3 days, you can safely return to work, school, and day care as long as your symptoms are getting better and you no longer have a fever.
Why trust our experts?
References
Centers for Disease Control and Prevention. (2024). Clinical overview of human parainfluenza viruses (HPIVs).
Faley, K. (2023). What is croup and what symptoms should you watch for in children? OSF Healthcare.
Petrocheilou, A., et al. (2014). Viral croup: Diagnosis and a treatment algorithm. Pediatric Pulmonology.
Smith, D. K., et al. (2018). Croup: Diagnosis and management. American Family Physician.
