Experts Explain What Your Mucus Color Means, and When to be Concerned

Experts Explain What Your Mucus Color Means, and When to be Concerned

If you’re blowing your nose regularly, it’s hard not to notice your mucus—and what color it is. So it can also be alarming if you happen to spot yellow, brown, bloody, or green mucus in your used tissue.

What does the color of your mucus mean, exactly? It turns out that your phlegm color can give you a little insight into how things are going with your health. And, while change in your mucus color will likely come with other symptoms that could clue you into what’s happening, seeing mucus that’s different from your usual hue could be a sign that something is off, says Elise Lippmann, M.D., a comprehensive ear, nose, and throat specialist at Massachusetts Eye and Ear. Here’s what you need to know.

What is mucus, exactly?

Mucus is a substance that covers the moist surfaces or your body, including your eyes, nostrils, lungs, and gastrointestinal tract, according to the National Institutes of Health (NIH). Mucus is so common in your body that the average person makes more than a liter of mucus a day.

Mucus contains trillions of microbes and works as a first line of defense against microorganisms that cause infections, the NIH says.

What color should mucus be?

At baseline, you shouldn’t really notice your mucus, says David Corry, M.D., professor of immunology, allergy, and rheumatology at Baylor College of Medicine. Still, “under normal, healthy circumstances your mucus should be clear,” Dr. Lippmann says. Worth noting, per Dr. Corry: Healthy mucus can also be white.

Your mucus can change color depending on what’s happening with your health and even in your environment, though. “Things like infections, nosebleeds, allergies, and environmental exposures such as tobacco use or heavy pollution can change the color of your mucus,” Dr. Lippmann says.

What do different mucus colors mean?

If your mucus color changes slightly from one nose blow to the next, you shouldn’t panic. But if you’re consistently noticing that your mucus color has changed, here’s what could be going on:

  • Yellow. Yellow or yellowish mucus can suggest that your body is fighting an infection. “It may be viral, such as a cold, or bacterial,” Dr. Lippmann says. “It is often a good sign because it means that the white blood cells in your body are doing their job to fight the infection.”

  • Brown. This is “usually a sign of old blood, which breaks down into different colors, including brown,” Dr. Corry says. That might be due to a previous nosebleed, but there are a few other things that can be behind brown mucus, Dr. Lippmann says, including tobacco use or even heavy air pollution.

  • Red or bloody. Blood-tinged mucus is usually from having dry nasal passages or getting hit in the nose, Dr. Lippmann says. “More rarely, it can be from growths in the nose,” she adds. You can even develop reddish mucus after eating red beets and foods with bright red food coloring, Dr. Corry says, “giving the false, but still alarming impression that blood is present.”

  • Green: Green or greenish mucus “often indicates a bacterial infection, which may require antibiotic treatment,” Dr. Lippmann says.

When should you call a doctor about your mucus color?

It’s important to pay attention to the symptoms that come along with a change in your mucus color, Dr. Lippmann says. “Fever, loss of sense of smell, pain or pressure in face, and nasal congestion can help determine whether treatment with antibiotics or other medication is indicated,” she says. Meaning, if you don’t have a fever or sinus pain along with your yellow mucus, your doctor will likely diagnose you with the common cold (although they’ll likely want to test you for COVID-19, just to be safe). But if you have intense pain or pressure in your face along with green mucus, your doctor may diagnose you with a severe sinus infection and prescribe antibiotics.

Brown or red mucus “should elicit greater alarm and a lower threshold for getting to the doctor,” says Dr. Corry. “Brown or bloody mucus accompanied by worrying signs like facial swelling and pain, altered vision, altered mental status, or high fever probably merits a trip to the doctor before the sun sets.” Without those signs, you can wait a few days to see if it resolves, he says—unless there’s a lot of bloody mucus. A cup or more, even without other symptoms? Go see the doc. Dr. Lippman adds that if you have a bloody nose that lasts longer than 45 minutes, that also warrants intervention.

So keep an eye on those tissues—they can tell you when it’s time to call the doctor.

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