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Dear Science: Why do I always get sick when the seasons change?

The short answer is yes and no and sort of and maybe a little. (Video: Gillian Brockell/The Washington Post)
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Dear Science, 

I'm so glad that it's finally fall — I love this weather. But as usual, I've got a cold. It seems like everyone gets sick as the seasons change. Is this true? Does “catching a chill” really make you sick, or is it something else? 

Here's what science has to say:

Are you really more likely to get sick when the seasons change? Kinda sorta. If we’re talking about colds and other upper respiratory infections, doctors say infection rates are fairly consistent throughout the year. But there are small upticks in cold and flu contagions in fall, winter and spring — when the weather is chillier.

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Allergies definitely do rear their ugly heads when the seasons shift, because different pollens and other allergens are wafting through the air. So as spring melts into summer, you might feel crummy more often because of all the flower pollen you come into contact with. As fall eases into winter, moldering leaves and dusty offices provide new allergy challenges. In addition, the dropping temperature proves friendlier for cold and flu viruses floating through the air. So during our two big seasonal shifts from hot to cold and back again, it seems like everyone has the sniffles.

And while cold weather can't make you sick — there's no such thing as catching a chill, so to speak — cold weather can make you more likely to get sick in several ways.

Cold, dry air cuts down on the healthy mucus that’s supposed to coat areas of your respiratory system, leaving airways more susceptible to unpleasant microbial visitors.

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“Colder temperatures also force you inside, which can increase disease transmission for a few reasons,” explained Alexandra Sowa, an internist at New York-Presbyterian Weill Cornell Medicine. “People are relegated to the indoors, where there tends to be dry heat and poor ventilation. Both of these have been postulated to increase disease transmission and susceptibility.”

So as fall creeps up and you have to pick between frigid, dry outdoor air and the stale, heated air of your home, your respiratory system suffers the consequences. But sniffling co-workers are an even greater concern.

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“Close quarters also mean more physical contact with others, so people are more apt to spread germs to each other,” Sowa said.

Meanwhile, that seasonal boost in allergies can irritate your lungs and nasal passages, making you even more susceptible to a cold or the flu, and making your symptoms seem even worse if you do get sick. Recurrent allergies can even lead to secondary bacterial infections in your sinuses, which could lead you to feel like you spend weeks or months at a time battling the same cold.

As for the adage that you might catch your death standing out in the chilly air, Sowa said, temperature can’t exactly make us sick. But some animal studies suggest that exposure to colder temperatures might make the body more susceptible to certain illnesses.

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“It is important to note that it isn’t weather that makes us sick, but the germs,” Sowa said. “This evidence supports the idea that we are more susceptible to getting sick from the germs in the colder weather.”

So, staying warm might not be the worst thing for your immune system. Keeping your airways moist with a humidifier at night — and treating seasonal allergies as they crop up, instead of just assuming you have an annoyingly persistent cold — can also help keep your mucus in virus-blocking shape and help cold symptoms feel less debilitating if a virus comes your way. As you spend more time inside, be mindful of good hand-washing practices and avoid too much contact with sniffling co-workers.

And don’t forget to get your flu shot!

Here's why the Center for Disease Control is pushing the flu shot this year. (Video: Monica Akhtar/The Washington Post)

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