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How Long Is a Virus Contagious?

July 24, 2019

A cold and the flu have a lot in common. To start with, they’re both caused by viruses that are spread through the air and on surfaces. A contagious person can send virus particles flying up to six feet in the air with a single cough or sneeze. Once they’ve landed, some viruses can live for a week or even longer.

Early cold and flu symptoms can be difficult to tell apart. Most colds are milder than the flu, perhaps with a low fever, coughing and congestion. Colds rarely require professional medical care, just rest and lots of fluids. But if you start feeling a higher fever with body aches and chills, you might have the flu. Reach out to your doctor if flu symptoms persist more than a few days because they could become something more serious.

Once you’re feeling better, it’s easy to think that you’re no longer contagious, but that’s not the case.

  • With the flu, you’re first contagious the day before you start feeling sick, and you can continue spreading the virus for 5-7 days after symptoms begin. And young children and those with weakened immune systems can spread the flu even longer. People with weaker immune systems may be less able to fully rid themselves of a virus, even if they’re feeling better.

  • With colds, you’re contagious 1-2 days before symptoms kick in and up to two weeks after exposure. Another important point about colds: just because your symptoms are mild, doesn’t mean you’re any less contagious — it could just be that your immune system is compressing your symptoms.

The best way to keep from spreading a cold or the flu is to stay home and limit physical contact with family and friends. And, since we don’t always know when a cold or the flu might be setting in, it’s important to take some additional precautions during cold and flu season:

  • Wash your hands thoroughly and frequently
  • Disinfect frequently touched surfaces
  • Cover your cough with a tissue or by coughing into the crook of your elbow
  • Be especially careful around older folks and those with weaker immune systems

Having trouble making sense of your symptoms? Check out these tips to help decipher between a cold or allergies, and the flu.