A runny nose is a sneaky thing. What might start out as a single cold-weather sniff or an itchy nostril somehow manages to elude further notice until it’s an all-out flood, pouring out in salty torrents down your upper lip as you shiver in the snow. Suddenly, you’re a runny-nosed kid again, helplessly chattering in the wind as snot globs onto your scarf.

This wintry fate is miserable — but not necessarily inevitable.

Figuring out how to stop a runny nose requires knowing what’s making it run in the first place. Your body is not leaking hot fluid out of your twin face-holes for fun. It’s doing it because, without the extra moisture, winter breathing would turn your lungs into a cold, arid wasteland, making them more prone to infections and irritation. Yeah. You’re welcome.

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Covering your mouth and nose locks in heat and moisture, giving the body fewer reasons to pump out fluids.

Thanks to the lubricating efforts of your nose and its associated tubes, the air that reaches your lungs is always warm and jungle-damp, allowing your lungs to exist in their natural, hydrated state. Under certain conditions, they have to work harder to maintain this internal tropical utopia. Dry air — which is often synonymous with cold winter air — tells the respiratory system to amp up its humidifiers, but sometimes your overprotective nose overcompensates and produces too much fluid. This excess of care is what ultimately drips out the end of your nose.

That’s not the only liquid chilling your nostrils, though. When it’s cold, your body also has to deal with the process of condensation. Imagine a bathroom after you take a hot shower: Steam swirls around and settles on the mirror, but once you open the door and let cold air in, that humidity condenses on the glass and starts to form droplets. The jungle heat you’re exhaling is like that steam, and blowing it out your nose in the cold is like pulling the bathroom door open. Cold air isn’t as good at holding moisture — again, that’s why your nose produces more fluid in the winter — so the water vapor in your exhalations condenses at the exact spot where your body heat meets the winter chill. Your nostrils are moisture’s last frontier.

Now that we know that all that excess nose juice is really just the body’s response to cold, dry air, we can reframe the runny nose problem more constructively: How can we keep our lungs and throats moist in the cold? If you’re outdoors, the best strategy is to trick your nose into thinking you’re someplace hot and damp: Wrap a scarf around your nose and mouth so the air you take in is relatively warm, and breathe through your nose so the air passing through has more time to heat up (mouth breathing takes in large volumes of cold air, which don’t have to travel as far to get to the lungs). You can pre-empt your nose’s instinctive gushing by snorting some saline nasal spray to moisten your breath holes. Your nose should stop running once you get back inside, but if your airways are really dried out you might want to help your body out by breathing in some steam.

Of course, there are other reasons tangentially related to cold weather that might cause your nose to run. If you have a cold or the flu, your nose isn’t secreting innocuous water to moisten your airways; it’s ejecting globs of mucus to flush lurking pathogens out into a tissue. If you are moved to tears by the severity of the winter, your nose will run because the excess fluid from the tear ducts on the inside corners of your eyes drains into the nasal cavity, and you essentially cry out of your nose.

This winter, don’t be that person with red, tissue-raw nostrils and a glistening upper lip, sniffling in the cold. Game your respiratory system with science by giving it what it wants: Warm, tropical air that’s as moist as a sauna. Whether it’s best to do that by way of a thick scarf, a terrifying balaclava, or a one-way ticket to Brazil, however, is

This winter, you don’t have to be that sniveling, raw-nostriled chump in the snow. Your body wants to feel like a tropical jungle, not a winter desert — and it’s within your means to make that happen sans snot. Whether you choose to do so with a thick scarf, a toasty balaclava, or a one-way ticket to Brazil, however, is totally up to you.

Keep the air around your nostrils warm to avoid a runny nose.
This balaclava-clad man looks scary, but at least his nose won't run.

Photos via Flickr / Mitya Ku

Yasmin is a writer and former biologist living in New York. A Toronto girl at heart, her writing also appears in The Last Magazine and SciArt in America. You might recognize her as a past host of Scientific American's YouTube series.