Myth Busters: Does Cold Weather Make You Sick?

Medically reviewed by University of Illinois-Chicago, College of Medicine on September 1, 2016Written by Jeanette Belliveau

Seeds of an old wives’ tale

Does cold weather make you sick? For centuries, this myth has led grandmothers to insist that kids sit away from drafts, keep a hat on in cold weather, and avoid going outside with wet hair.

But if this is a myth, why do colds and the flu peak in the winter? The answers are complex and fascinating.

The culprits

In terms of infectious illnesses, germs make you sick, not cold weather itself. You have to come in contact with rhinoviruses to catch a cold. And you need to be infected with influenza viruses to contract the flu.

Rhinoviruses peak in spring and fall, and influenza viruses peak in the winter.

While there isn’t a connection between being chilled and getting sick, cold air may contribute to conditions that lead to illness.

Central heating

Cold air forces you inside where it’s warm. Dry air associated with central heating makes it easy for cold and flu viruses to get into your dry nasal passages.

But thoughts on whether this theory is correct are divided.

Indoor humidity and ventilation

Dry indoor air itself doesn’t get you sick. But it may play a role in letting aerosol droplets from a sneeze survive and prosper.

Researchers at Tianjin University in China found students in dorm rooms with poor ventilation caught more colds.

Additionally, researchers at Virginia Tech found that good ventilation, as well as high indoor relative humidity, renders the influenza A virus inactive.

The great outdoors

Dry air outdoors, as measured by absolute humidity, may also be linked to flu outbreaks.

According to The National Institutes of Health (NIH), dry winter air allows the flu virus to survive and transmit itself.

Additional NIH research suggests that the flu virus’ coating becomes tougher at temperatures close to freezing, making them more active, more resilient, and easier to transmit in the winter.

More clues to why you’re sniffling

It’s likely that being outside in cold weather inhibits the ability of mucus and nasal hairs to work disease agents out of your nose.

It’s also likely that when you get back inside, in a room with the windows shut and people sniffling, that you are more likely to be exposed to germs.

As people return to college, school, work, and day care in the fall, viruses find ideal conditions to hop from one host to another, before cold weather even sets in.

The perils of hypothermia

Hypothermia occurs when your body loses too much heat. This can result from exposure to cold weather and elements. It’s an emergency that requires immediate medical care.

Exposure to cold temperatures can cause hikers, the homeless, the very young, and the very old to begin to shiver, become confused, and even lose consciousness.

If you are in cold weather and encounter any of the following conditions, you will quickly face a medical emergency:

  • being exposed to a lot of wind or rain
  • becoming sweat-soaked
  • being submerged in water

If your body loses too much heat, get warm and get help.

Cold weather and asthmatics

If you like to run but have a history of asthma or upper respiratory conditions, cold weather can create problems. Warm up gradually before hitting your full stride outdoors, and wear a neck gaiter over your mouth to help warm the air going into your lungs.

Also plan your route so you avoid likely triggers for your asthma, like leaf burning or chimney smoke.

Implications of the myth

People who truly believe cold weather causes infectious sicknesses may not understand how germs affect the body.

Research at George Washington University found that young children are more likely to believe that cold weather causes illness. This means that children may not understand the best way to prevent getting sick from colds and the flu.

Knowing how germs work can help health educators teach effective prevention of colds and the flu, such as promoting good hand hygiene.

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