The mucus on your tissue matters.

So your nose feels a little runny or sniffly. You reach for the Kleenex—and when you blow into it, you notice that the snot on the tissue is green. Hmm. Usually it's white, or maybe a little yellow, so what does it mean that you're now seeing green? Health spoke with doctors to find out why green snot happens, and what you should do about it.

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Credit: Getty Images

What does green snot mean?

"Green snot typically means that your immune system is trying to fight off an infectious agent," Cory Fisher, DO, a family medicine physician at Cleveland Clinic, tells Health. That infectious agent is probably a virus, but it could be bacteria, Dr. Fisher adds.

What exactly causes nasal mucus to change to a gross color? Pin the blame on body chemicals that fight infectious bugs. "White blood cells called neutrophils are the body's way of fighting infection," Philip Chen, MD, an associate professor of otolaryngology and rhinology at the University of Texas Health San Antonio, tells Health. "These cells release chemicals to fight infection and they can be colored, resulting in colored mucus."

What color should snot be?

Generally, snot is clear, Dr. Chen says, "but some mild coloration is not typically cause for alarm." Basically, the color of your nasal mucus alone doesn't clue you into anything specific about your health. Even brown snot can be normal. "Brownish mucus can also occur when [the] air is dry and small amounts of blood are in the mucus," he explains.

Does snot turn a different color when you have a cold or other infection?

It can, but not always. "Sometimes there will be a white tint," says Dr. Chen. "At times, it can be yellow, green, or sometimes a mix of these colors. None of these are tell-tale as to what kind of infection you have." While the color might not change if you've caught a cold or flu, other characteristics of your snot might. "Oftentimes with a common cold, the mucus is clear—no color or tint—but is typically stickier and thicker than usual," he says.

When should you see a doctor about your snot?

Patients who are concerned about the color of their snot are typically also worried about other symptoms. "Color alone is not usually what prompts a doctor's visit," says Dr. Chen.

So if it's just green snot you're seeing but you otherwise feel fine, you can likely skip the doctor visit. But if your nasal mucus is looking green and your nose is stuffed up or runny, you have head or body aches, and feel feverish, you can assume you're coming down with something. If some of these accompanying symptoms are serious enough, check in with your doctor.

Green mucus is not a sign of COVID-19 according to the Centers for Disease Control (CDC). But a runny nose or congestion can be, per the CDC. So if you're blowing your nose a lot or are all stuffed up and have other COVID symptoms such as a sore throat, cough, and shortness of breath, and COVID is a possibility, consider alerting your MD.

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