What Causes Those Sniffles? The Science Behind the Common Cold

The name “common cold” is a little vague, so let’s break it down.

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For most people, the common cold makes a visit almost every year—or even multiple times a year—causing coughing, congestion, and sneezing. And it’s called “common” for a reason: The United States sees about a billion colds each year, making it possibly the most common ailment—literally.

Despite its ubiquity, most people don’t actually know what the common cold is. Sure, you recognize the symptoms—but what’s actually causing the cold, and why is it called a cold in the first place?

What is the common cold?

Like the flu, a cold is caused by a virus, but thankfully, it’s much less threatening than the influenza virus. Like other viruses, it invades the body through the nose or mouth, either by inhaling tiny particles in the air from an infected person’s cough or sneeze, or by touching your mouth or nose after contact with a contaminated surface or object.

Once the virus invades, you have an infection of the upper respiratory tract, including your nose, sinuses, and throat. Cold symptoms are caused not by the virus itself, but by the immune response in the upper respiratory tract as it tries to fight off the virus, causing acute inflammation.

Normally, infections are named after the virus that causes it, but there’s no “cold virus.” The common cold can actually be caused by hundreds of different viruses, so it’s technically not one specific disease, but a category of illnesses that bombard you with similar symptoms. The majority of cold-causing viruses are called rhinoviruses, according to the Centers for Disease Control and Prevention.

Because so many different viruses can cause a cold, you can get the cold numerous times. Each time you get the common cold, you only gain immunity to that specific virus strain, but you can get another cold a month later from a different cold-causing virus.

That’s why you can catch a cold literally hundreds of times throughout your lifetime. It’s normal for adults to get the cold two or three times each year—and children can actually come down with the cold as much as 12 times (!) a year, according to UpToDate from Wolters Kluwer. Of course, some people go years without the cold, and others seem to get it constantly. Here are reasons you always seem to catch a cold.

So why is it called “the cold?” Apparently, this name came about in the 16th century because the symptoms mimic how your nose gets all sniffly when you go outside in the cold. Who knew?

The cold might not be dangerous (and complications are rare), but symptoms can be unpleasant and cause you to miss out on life. Find out how to prevent the cold here, and check out these cold treatment tips here.