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Can You Really get Sick from Going Out in the Cold with Wet Hair?


Posted: 1/17/2017
Can You Really get Sick from Going Out in the Cold with Wet Hair?

Remember when your mother used to tell you not to go outside with wet hair or else you would catch a cold?  Did you ever wonder if that was even true?  So did we!  That's why we set out to find the truth once and for all.

Can you catch a cold from going outside with wet hair in the winter?

In short, the answer is no.  Body temperature, by itself, will not cause a cold.  You catch a cold when a virus makes contact with mucus membranes and triggers an immune response.  Wet hair will have no effect on your ability to come into contact with a virus.  However, if you went outside with wet hair, no jacket, and no shoes you could catch hypothermia, which would be much worse than a cold, and can even be fatal.

Where did this myth come from?

Nobody knows for sure.  One theory is that it dates back to an experiment done by famed scientist Louis Pasteur in 1878.  Pasteur set out to see if cooling the body of a chicken would make it susceptible to the anthrax virus.  Chickens have a natural immunity to the disease.  In the experiment, Pasteur dunked a chicken into cold water to cool it's body temperature, and infected the chicken with anthrax.  The chicken died.  He repeated the experiment and the second chicken also became ill, but did not die.  The results of the experiment seem to show a correlation between getting cold and wet and becoming ill.  However, the reason Pasteur had to lower the body temperature of the chickens is because their natural body temperature is between 104-107°F, which is too hot for Anthrax to survive, thus their immunity to anthrax.

Another possible reason the myth has prevailed is due to the results of a study done by a German scientist following World War I.  The study found that soldiers stationed in cold wet trenches for 72 hours were 4 times more likely to catch a cold than soldiers who were stationed in warm barracks.  However, numerous studies have been done since this initial study and have not been able to recreate  the results.  In fact, subsequent studies have shown lowered body temperature does not increase the chance of catching a cold whatsoever.  It is also possible this myth continues to prevail due to the belief in another myth: the myth that you lose most of your body's heat through your head. (spoiler alert: that's not true either)

Is there any truth to this myth at all?

Maybe.  While being cold and wet won't get you sick, certain cold viruses do thrive in a colder climate.  The virus that is most responsible for causing colds, the rhinovirus, prefers a colder climate and studies have shown there is a correlation between colder temperatures and increased rhinovirus infections.  Low humidity is also a factor in the frequency of rhinovirus infection even though the rhinovirus thrives in a more humid environment.  It is believed the low humidity evaporates moisture from virus-containing droplets (from a cough or a sneeze) allowing them to travel farther and increase the chance they infect more people.  So while there is an increase of incidence of the common cold in winter, it is due to the air temperature and humidity, not body temperature and immune response.

In winter time, the incidence of rhinovirus goes up, and there are several theories as to why this is.  Aside from the lower temperature allowing rhinovirus to thrive, low temperatures also make people spend more time indoors than they would when the weather is nice.  This puts us in close proximity with one another; so when one person catches a cold, they are much more likely to spread it to others.  The low humidity in winter not only helps the rhinovirus travel further, but it dries the mucus lining in the nose.  It is believed the dry mucus membrane in the nose may be more susceptible to infection by the rhinovirus.

What really causes a cold?

When virus-containing water droplets from a sneeze or a cough enter your body and makes contact with the mucus membrane, the immune response is triggered.  The rhinovirus thrives in lower temperatures (around 89°F) and high humidity which happen to be the living conditions inside the human nose.  Once inside the nasal cavity, the rhinovirus attaches itself to the nasal lining and begins replicating.  This is what causes the runny nose, stuffy nose, sneezing and extreme nasal mucus expulsion of a rhinovirus infection.  This is also how the rhinovirus gets its name, "rhino" being the Greek word for nose.

Conclusion

Many conditions of colder winter weather help to make us more susceptible to catching a cold this time of year.  While certain behaviors, like sneezing or coughing into the crook of your elbow, can affect how susceptible we are to catching a cold, leaving the house with wet hair is not a factor.  While it is a good idea to keep your head covered in order to stay warm in cold weather, going outside with wet hair and no hat on a cold winter day will have no affect on your ability to catch a cold.  It's science.


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