Is the Common Cold a Bacteria or a Virus?

You’ve got a cold. Time to curl up on the couch, stream your favorite show and wait for the decongestants to kick in. Unless there’s an antibiotic you could take to speed things up, right?

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Wait a minute: Would that work? Is the common cold a bacterium or a virus?

Infectious disease specialist Jessica Lum, MD, explains that while they can cause similar symptoms, bacterial and viral infections are treated very differently. And the cold that’s bumming you out? It’s a virus.

Is it a bacterial or viral infection? Learn how to tell the difference and what to do about each so you can feel better faster.

Is the common cold caused by bacteria or viruses?

Different viruses, such as rhinoviruses, cause the common cold. Colds don’t respond to antibiotics because they’re not bacterial infections. And the symptoms tend to be mild enough to handle at home with over-the-counter medications.

“For the most part, most viruses that cause the common cold resolve on their own, as the immune system is generally capable of clearing the infection without specific antiviral treatment,” Dr. Lum says. “But if you have a weakened immune system, these infections may last longer and be more severe. So, it’s important to discuss them with your doctor.”

How does the common cold spread?

The viruses that cause the common cold can spread in three different ways:

Direct contact: Getting up close and personal with someone who’s sick — even if they aren’t showing symptoms yet — is one of the easiest ways for cold viruses to spread. That means shaking hands, hugging, kissing … you get the idea.
Respiratory droplets: When people cough, sneeze, talk and breathe, they release tiny droplets into the air. If they have a cold, those droplets are also packed with virus particles. If you breathe them in, you could end up getting sick.
Contaminated surfaces: When germ-covered hands touch doorknobs, desks and dishes, they leave the cold viruses behind as a souvenir. Those germs can live on surfaces for up to 24 hours. If you touch a contaminated surface and then touch your face, you could contract the virus.

Why don’t antibiotics work for the common cold?

Antibiotics only treat bacterial infections. They won’t help kick viral infections like the common cold.

If you’ve got a stubborn bug, you may be tempted to ask for antibiotics anyway. But Dr. Lum says that overusing antibiotics, especially when they’re not useful, is problematic.

“When we overuse antibiotics, the bacteria they’re meant to treat become more resistant. Eventually, those treatments could stop working altogether,” she explains.

Antibiotics can also destroy the “good” bacteria in your gut, causing diarrhea and other gastrointestinal troubles.

“Your gut is full of bacteria that keep you healthy. But antibiotics do not know friend from foe,” she continues. “It will kill the bad bacteria that’s causing the infection, but it will also kill the good bacteria in your gut that helps you digest food.”

It’s a sacrifice worth making to treat a bacterial infection. But if you have a common cold, an unneeded course of antibiotics is a waste of a perfectly good microbiome.

Can a cold turn into a bacterial infection?

A cold can’t transform into a bacterial infection, but it can kick off a secondary infection.

For example, bacteria can grow in the mucus that builds up in your nasal passages when you’re sick with a cold. In some cases, the result can be a nasty sinus infection.

Dr. Lum says you may have a secondary bacterial infection if:

Your cold symptoms haven’t improved — or they got better and suddenly worsened.
You have a fever or chills.
You’re having respiratory issues, like wheezing or shortness of breath.
You have intense pain in your ears, throat or sinuses.

“Bacterial infections can be more severe and may require antibiotics to get over,” she adds.

Time heals

If you’re dealing with everyday common cold crud, you’ve got a virus. And the best prescription for it isn’t antibiotics. It’s rest, fluids and patience.

“With the help of over-the-counter cold medicines for symptom management, you should be feeling more or less like your old self again in seven to 10 days,” Dr. Lum reassures.

“If you aren’t on the upswing by then, it’s time to reach out to a provider. They can check to see if you’ve developed a secondary infection.”