Fascinating facts about people, places and things
Girl blowing snowflakes in a snowy forest wearing a fur-lined hood and gloves.
Rare & Remarkable Human Traits

Why Does Cold Weather Make Your Nose Run?

Cold air makes your nose run because it overworks its built-in humidifier. Learn how the nose warms and moistens air, and why it overshoots.

By Written Facts Staff7 min read

You step outside on a crisp fall evening, maybe walking a trick-or-treater down the block, and within minutes your nose is dripping. You don't feel sick, and you aren't. Your nose is doing its job, which is to warm and moisten every breath before it reaches your lungs. Cold, dry air makes that job much harder, and the nose overcorrects. The extra moisture has nowhere to go but out.

The short answer

The inside of your nose works like a climate-control system. Whatever air you breathe in, it heats and humidifies it on the way down. On a warm, humid day that takes little effort. On a cold, dry one the nose has to push in much more heat and water, and it often pushes in more than it needs. The surplus runs out of your nostrils.

The condition is common enough to have names. Doctors call it "cold-induced rhinitis," and it's also known as "skier nose." According to David King, a senior lecturer at The University of Queensland, about 50 to 90 percent of people get a runny nose when it's cold. In a small study of skiers, 48.6 percent of the participants had cold-induced rhinitis, and almost all of them (96 percent) named a runny nose as their main symptom.

Harvard Health puts it simply: a runny nose in winter isn't automatically a sign of illness. It usually means the nose is preparing the air for your lungs.

What your nose does with every breath

Inside your nose are folds of tissue called turbinates, with a dense supply of blood vessels. As air passes over them, those vessels warm it to near body temperature and add moisture, all within seconds, according to the Allergy & Asthma Network.

The results are impressive. King writes that air at the back of the nose is usually about 26°C (79°F) and can reach 30°C (86°F), with humidity around 100 percent. That holds even when the air outside is well below freezing. By the time a breath leaves the nose, it has gone from cold and dry to warm and saturated.

The moisture comes from a wet lining kept supplied by glands and blood flow. The Allergy & Asthma Network estimates that the nose makes about 2 to 4 cups of mucus a day. Other estimates differ, and some put it closer to a pint or a quart. King estimates that the nose can lose up to 300 to 400 mL (10 to 13.5 fluid ounces) of fluid a day just from humidifying air.

So on a normal day your nose is already handling a lot of fluid. Cold weather increases the demand, and that's where the dripping starts.

The chain reaction in cold air

When cold, dry air hits the lining of your nose, several things happen in quick succession.

  1. Nerves raise the alarm. King explains that cold, dry air stimulates nerves inside the nose, which send a message to the brain. The brain responds by increasing blood flow to the nasal lining, which brings more heat. Mucous glands then add more secretions.
  2. Immune cells join in. The same air also stimulates mast cells, immune cells in the nasal lining. They release chemicals that increase fluid production further.
  3. Evaporation cools things down. Turning water into vapor takes a lot of heat. As moisture evaporates into the incoming air, it pulls heat from the nose and cools the lining. The nose responds with still more blood flow.
  4. The system overshoots. In King's words, when this compensating mechanism is "a little too overactive," the moisture beyond what's needed drips from the nostrils.

Evidence that nerves are involved comes from drug studies. In a small 1987 placebo-controlled trial with 14 volunteers, a nasal spray of ipratropium, a drug that blocks a nerve signal that drives gland secretion, reduced cold-air-induced runny nose by 73 percent. That fits a reflex that runs through the nerves.

Researchers have also looked at a cold sensor called TRPM8. It's a channel on cell surfaces that responds to cooling and to menthol, which is why mint feels cold. Researchers found TRPM8 in cells of the nasal lining, and cooling those cells to about 24°C, or applying menthol, triggered the release of mucin, a main ingredient of mucus. That makes TRPM8 one plausible suspect.

Scientists haven't settled the exact pathway. Nerves, mast cells and gland secretion all appear to be involved, but how much each one contributes, and which sensors start the process, is still being worked out.

Why some people drip more

Not everyone's nose reacts equally. According to King, people with asthma, eczema and hay fever seem to experience cold-induced rhinitis more. Their mast cells are usually more sensitive, and their blood vessels tend to react more strongly.

That stronger reaction can go beyond dripping. In more sensitive people, King notes, cold air can also cause a stuffy nose and even sneezing. The swollen blood vessels that warm the air also take up room inside the nose, which narrows the airway and causes congestion. So if you're prone to allergies and find that a cold morning leaves you sniffling, sneezing and stuffed up at once, you're in the group this reaction tends to hit hardest.

Cold weather versus a cold

A runny nose from a cold and a runny nose from cold weather look the same in a tissue, but they happen for different reasons. During a cold, Harvard Health explains, the extra mucus has a defensive purpose: it helps flush out the germs causing the infection. A cold-weather drip is the nose doing its normal air-conditioning work, just more than usual.

The timing helps tell them apart. A cold builds over days and often brings other symptoms. A cold-weather drip shows up within minutes of going outside and usually stops soon after you come back into the warmth, often before you've taken your coat off.

What helps

For most people the answer is simple. King writes that treatment usually means carrying some tissues or a handkerchief. It's worth keeping some in a coat pocket for a Halloween walk or a chilly November football game.

For people who are bothered more often, there's a medical option. Nasal sprays that block the nerve signal behind gland secretion, such as atropine and ipratropium, have been tried with some success, along with anti-inflammatory sprays. Ipratropium has the most evidence. Besides the 1987 cold-air trial, a 2023 review of five randomized trials with 472 people who had nonallergic rhinitis found that a 0.03 percent ipratropium spray reduced runny nose more than a placebo. Mayo Clinic's drug information lists the 0.03 percent spray for runny nose from allergic and nonallergic rhinitis. It notes that the spray doesn't relieve congestion or sneezing and is available only by prescription.

Evidence aimed specifically at cold-weather runny nose is still limited to a few small studies. If your nose runs often, keeps running after you're back indoors, or comes with other symptoms, a doctor can help figure out whether something besides cold air is involved.

Sources (9)

Photo by 822640 on Pixabay.