Mucus may be a little gross, but it's also a key player in your body's defense system.
Woman blowing runny congested nose spring allergies cold symptoms
Credit: Getty Images

When you’re under the weather, a stuffed-up nose can be the source of much misery. But as you reach for your thousandth tissue, it may help to know that all that snot plays a crucial role in getting you well again.

So what exactly is that phlegm? As a recent video from the American Chemical Society explains, the goop contains cells and chemical compounds that help fight off whatever bug is making you ill. “When we get sick with a cold or sinus infection, our bodies begin to produce more mucus than normal to double down on the viral or bacterial invaders,” the narrator points out.

The color and consistency of your mucus change too—and the stuff in your used tissues can offer clues about what’s happening in your system. “Yellow or white mucus turns up when you’re congested, and a higher concentration of living and dead white blood cells have thickened the discharge,” the narrator explains. "Those immune cells might be there to battle a cold, so slow down and take it easy."

Got greenish phlegm? That means it’s full of white blood cells called neutrophils and an enzyme they produce, a sign your body has ramped up its defenses against the invaders.

For more helpful facts—and tips about which treatments are best for your symptoms—check out the video below.

Remembering the germ-destroying mission of your mucus may make that runny nose seem slightly less miserable.

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