How Long Is a Cold Contagious? Here's What Experts Say
Unfortunately, you may not be in the clear as soon as your nose stops running.
The common cold is—as the name suggests—incredibly common. In fact, the US sees about one billion cases of the common cold each year, according to MedlinePlus, a resource from the US National Library of Medicine. That number is largely attributed to number of viruses that can cause a cold—about 200 or so, per the National Institutes of Health (NIH), including rhinoviruses, adenoviruses, and coronaviruses.
But colds are also extremely contagious. The Centers for Disease Control and Prevention (CDC) says they can be spread through the air, close contact with infected people, and even through an infected person's fecal matter (say, if they don't properly was their hands after using the bathroom.
You can take all the necessary steps to protect yourself—washing your hands with soap and water, avoiding touching your face, and staying away from sick people—but chances are, you'll still cross paths with a cold virus and come down with something. But even in that case, you can still take steps to protect someone else from the fate that befell you—and that has a lot to do with knowing how long cold viruses last and how contagious they are.
First, the basics: MedlinePlus says the incubation period of a cold—or the amount of time between when you're infected and when you begin to show symptoms—is about two or three days. Unfortunately, it's during that time when you may be most contagious, Jazmine Sutton, MD, a hospital medicine specialist at Cleveland Clinic, tells Health. “Most common colds are caused by viruses and the highest infectious period is usually one to two days prior to symptom onset and during the first two to three days of symptoms,” she says.
Those symptoms Dr. Sutton is referring to are just typical cold symptoms: sore throat, runny nose, coughing, sneezing, headaches, and body aches. (Just FYI: while some colds can cause an elevated body temperature, fevers are more commonly due to the flu, COVID-19, or other viruses.)
Once those cold symptoms show up, they can last anywhere from a few days to up to two weeks, per MedlinePlus—and in the majority of cases, a cold is most often not contagious after the first week.
But that's not always a hard-and-fast rule; as long as you're still coughing or showing symptoms of any kind, you may still be contagious. “Sometimes, you may have a nagging cough that lingers for an additional week or two” after you’ve started feeling better, Dr. Sutton says. And in rare cases, Dr. Sutton says, you can still be infectious even after symptoms resolve, due to something called viral shedding, or when a virus replicates in the body and makes its way out into the environment.
Basically, your best bet for protecting yourself and others during flu season: Continue taking the necessary preventative measures like hand washing and physically distancing yourself from sick people. And if you do come down with a cold, it may be wise to track your own symptoms and try to isolate as much as possible during the first few days when a cold can be most contagious—and remain vigilant after that, until you're back to feeling 100%.
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