Why We Sniffle

Does Science Know What Makes Your Nose Run?

A little girl blowing her nose with a tissue.

When you’re sick with a cold, your face oozes a brilliant defense — but an inconvenient one. Excess mucus can be a sign of an immune system in action. But where do runny noses come from? What’s the science behind the sniffles?

Take a hard breath through your nose. What do you hear? A clear, whistling whir? Or a wet tumbling crackle? If your nose is clear, your immune system is working. If you have the sniffles, your immune system is working even harder.


Before it’s allowed into your lungs, air passes through a warm, sticky filtration system of hairs and mucus — also known as your nose. This mucus and hair trap things like particulates, viruses, and bacteria before they make it down into your chest. Cilia, the microscopic hairs in the back of your nose, then escort that pathogen-filled mucus toward the throat where it can be gulped.


That’s when you’re healthy.

Cilia pass the pathogen-trapping mucus away from vulnerable parts of the respiratory system.


The Most Common Symptoms of the Common Cold

Things get a bit more dramatic when a virus makes it through this first line of immune defense and infects our cells. Our noses begin to act differently; in short, they start to run.


Once triggered, small messenger proteins called cytokines do what they’ve been doing for millions of years. They silently summon T cells and B cells to eradicate the pathogen. They also tell glands in the mucous membrane of our nose to, not so silently, secrete more snot — a condition scientists call rhinorrhea.

Snot is made by mucosal glands that line the respiratory tract.


This is meant to flush any additional pathogens that may be trying to infect us. Other common symptoms of our immune response are fevers, meant to overheat the viruses, and coughing and sneezing, which are both attempts to forcibly eject pathogens from our nasal passages. But these symptoms can be overbearing, and they aren’t entirely necessary.

Do Runny Nose Medications Slow Our Immune System Down?

The symptoms of inflammation we feel — and the sniffles we sniffle — during an infection steal energy from the more important microscopic battle happening at the cellular level. 


“There's no need for you to suffer through those symptoms. The immune system has kicked in. Your body is already fighting the infection,” says Dr. Kizito Kyeremateng, Doctor of Pharmacy and Senior Medical Manager at Bayer Consumer Health.


“If you have a runny nose, first-generation antihistamines like those found in many cold medicines can help, because of their anticholinergic properties,” he says. “Anticholinergic agents can dry the liquid out.”

These medicines do not affect our body’s ability to fight the virus, he says. They reduce the burden of symptoms as our immune system does its brilliant work throughout the infected cells.

runny nose
Over 500 million noses get the sniffles every year.


Supporting the Immune System

As we’ve seen, our first line of immune defense is made up of proteins, special cells and the surfaces of our body that come into contact with the outside world — surfaces like the inside of our nose and our skin, as well as the microbes that live on its surface.


Our immune defense’s second and third layers aren’t as easily felt or observed, but it’s crucial we don’t ignore them. It’s something we can support. Proper nutrition, exercise, vigilant hygiene, and nurturing our mental well-being are all good ways to give our immune system the tools it needs — especially during the times of year that common cold viruses are circulating. 


Taking supplements can also help optimize immune performance and support the recovery process.


Micronutrients That Support Immunity

  • Vitamin C — An antioxidant that aids the function and movement of a wide range of immune cell types
  • Vitamin A — Helps maintain the integrity of the tissue that lines much of our respiratory tract
  • Zinc — Thought to inhibit the replication of respiratory viruses, though its exact mechanism is unknown
  • Vitamin E — An antioxidant that may help boost the ability of white blood cells (lymphocytes) to respond effectively to viruses

Next time you sniffle, just know it could be a sign that your body is fighting to protect you, but you don’t have to suffer through it. We can overcome a runny nose with time-tested medications and the science of snot.

4 min read