Every cold I get sets off a string of internal debates: Is this actually a cold? When is a cold contagious, even? Should I stay home from work? Why are my symptoms hanging around for 700 years? Am I still contagious when they’re gone? Is this even the same cold or have I moved onto a whole new cold because winter is a never-ending hellscape of sickness???
Your internal monologue might not be as spirited (read: anxious) as mine, but I’m guessing you’ve probably asked yourself at least some of the same questions. Most of us don’t want to be that person who spreads their germs around, so I try my best to quarantine myself when I’m a coughing, sneezy, or sniffling mess. But, admittedly, it didn’t occur to me to wonder until recently: Wait, is my cold still contagious after my symptoms go away?
In the spirit of being a conscientious (and non-contagious) human, I chatted with some infectious disease doctors to get to the bottom of it. Here’s what I found out.
First, here’s a refresher on the common cold.
Ah, the common cold. We all know and hate its symptoms. Battling a runny or stuffy nose, sore throat, cough, mild body aches, sneezing, low-grade fever, and general malaise probably isn’t your favorite way to spend some time.
To get technical about it, the common cold is a viral infection of your nose and throat that can be caused by a whole bunch of different viruses (though rhinoviruses are most common). This is why it’s annoyingly possible to find yourself catching multiple colds throughout a season, William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine, tells SELF.
On top of being The Worst to deal with, colds are also pretty dang talented at spreading around. As Dr. Schaffner explains, a cold virus enters your body via your mouth, eyes, or nose (ugh) in one of two ways: through little particles in the air spread by sick people or through contact with a contaminated object. Meaning, if someone talks, sneezes, or coughs around you, you might breathe in their virus, but you might also get it from something like a doorknob a sick person recently touched or by shaking their hand, then touching your mouth, eyes, or nose. (To be clear, we’re just talking about the common cold here—details about things like transmission and contagiousness vary when you’re talking about other illnesses, like bacterial infections and the flu.)
“[Cold viruses have] developed a very efficient way to get around and circulate through a population,” says Dr. Schaffner. “That’s why colds are so ubiquitous.”
So, when is a cold contagious?
Since symptoms are the most obvious sign that you’re sick, it makes sense to assume that there’s a direct correlation between signs of illness and how contagious you are. The grosser and more symptomatic you are, the more contagious you must be, right? Well, not exactly.
Your cold symptoms are the physical manifestations of all the hard work your immune system does to fight off the virus. For example, a cough is often a reflex to help bring up mucus containing the virus in question, Tania Elliott, M.D., clinical instructor of medicine and infectious disease at NYU Langone, tells SELF.
When a virus enters your system, it can take up to 72 hours for your body to rev up and mount this response. Since the virus is in your body and actively multiplying during this incubation period, the experts we spoke to think there’s a good possibility you could be contagious a day or so before your symptoms even show up. That said, this isn’t totally proven.