Will you catch a cold if you go out with wet hair in cold weather? If you say no, you are correct. Colds and pneumonia are
caused by infection. You do not pick up infections from cold
weather, you get germs from other people who sneeze or cough in
your face or transmit germs with their hands to objects that you
So the question is whether chilling the body suppresses
your immunity so that germs that you can normally control
suddenly become pathogens and make you sick. That question has
been answered many times. Chilling does not hinder your immunity
as long as you are not so cold that your body defenses are destroyed.
In 1958, a paper in the American Journal of Hygiene (Volume 68)
reported that more than 400 volunteers were exposed to viruses
that cause colds. Some were exposed to very cold temperatures
while wearing heavy coats, some to 60 degree temperatures while
wearing underwear, and some to a very warm 80 degrees. All had
the same rate of infection. A 1968 paper in the New England
Journal of Medicine followed inmates at a Texas prison who had
the cold virus placed directly into their noses. They were then
exposed to extreme temperatures, with varying amounts of
clothing. Being cold or warm, being dressed or undressed, or
having wet hair or dry hair had no effect on their infection rate.
The crucial factor that determines whether you get a cold is
exposure to the cold virus.