“Don’t go outside with a wet head or you’ll catch your death of cold!” It’s a warning that’s been passed from one generation of parents to the next.
No doubt you’ve heard this one before from your mother as you rushed out the door one winter morning fresh out of the shower. However, unless you are so cold that you get hypothermia, which could make you susceptible to infection, wet hair or clothes won’t increase your vulnerability.
You will probably feel chilly if you skip the blow-dry on a cold day but not much else will happen. Venturing out into the cold with a wet head doesn’t condemn you to illness. Viruses cause colds and the flu. You need to be exposed to the cold virus in order to get sick. More than 200 different viruses can cause colds, but the biggest culprit is the rhinovirus.
“In order to get an infection you need to be exposed to an infectious agent,” said Dr. Pritish Tosh, an infectious diseases physician and researcher at the Mayo Clinic. “There are several things that circulate during periods of cold weather — influenza, different cold viruses. That’s what you need to get infected. Going out with wet hair is not going to cause an infection. I think it more so just makes people uncomfortable.”
When someone sneezes or coughs and isn’t kind enough to cover his or her mouth and nose, droplets containing the cold virus escape out into the air. If you’re close enough to some of these droplets, there’s a good chance you’ll soon be coming down with a cold. Viruses also can live on sinks, counters and other surfaces, which means you can catch a cold if you touch an object that was recently handled by someone with a cold, and then put your hands on your nose or mouth.
Who started this familiar maternal refrain? Part of the blame may rest with French chemist Louis Pasteur, who in 1878 exposed chickens to anthrax and then dipped their feet in icy water to see how it might affect their odds of catching the disease. The chickens developed anthrax and died. When he repeated the experiment but wrapped the exposed chickens in a warm blanket, they survived.
Human studies in the early 20th century seemed to confirm Pasteur’s research. A German scientist discovered during World War I that soldiers who slept in cold, wet trenches were four times more likely to get colds than those who rested in dry barracks. Somewhere along the line, a few mothers must have caught wind of these studies and began forbidding their children to step foot outside until their heads were bone-dry.
It’s also possible that people who believe that a wet head will lead to a cold have heard that a good percentage of the body’s heat escapes through the head. That is a myth. In actuality, you lose just as much, if not more heat through a bare arm or leg as you do through your head.