How Long Are Cold, Flu Symptoms Contagious?
MINNEAPOLIS (WCCO) -- State health officials say Minnesota is in peak influenza season. It's also been a busy time of year in doctor's offices for the common cold.
That has Celeste from Golden Valley and Morgan from Minneapolis wanting to know: How long are you contagious with the viruses? Good Question.
"You're probably contagious for a few hours before you get symptoms, but not for very long," says Dr. Mark Schleiss, director of the Division of Infectious Diseases and Immunology at the University of Minnesota Medical School.
He says people who get influenza are generally contagious for three to four days after symptoms hit. The first 24 hours are the most contagious.
When it comes to colds, Dr. Schleiss says how long a person is contagious is harder to determine. While influenza generally comes on suddenly, the beginning of a cold can last for hours or days. He says people are generally contagious with most common colds for four to six days.
"My usual rule of thumb is to stay home until you're not coughing, not running a fever and when you feel better and well enough to work," he says.
The viruses are usually spread in different ways. Influenza is more likely to spread through droplets in the air. Researchers at MIT found sneezes can travel across a room, but the large droplets drop off by six feet.
"We have a three feet rule," says Dr. Schleiss. "If you're closer than three feet from someone, your chances go up substantially."
Cold viruses are different. They are more likely to spread when infected hands touch a person's eyes or nose. Studies of human behavior have found people touch their eyes and nose each day more often than they think.
Dr. Schleiss says viruses can also live on hard surfaces for several hours, but a person is more likely to catch a cold from shaking hands than from touching a doorknob.
He stresses people should get a flu shot, stay home when they're sick and wash their hands more often than they think they should.
"The longer, the better," he says. "But, if it is a quick scrub it's worth the time and trouble to do it frequently throughout the day."
