Why does a nose run? Because the nose makes mucus, also called snot. It is a sticky, slimy stuff. The clear, thin kind is normal and healthy, and everybody makes it. As of November 2026, experts say the nose and sinuses make about a quart (about 1 liter) a day. Nobody knows the exact amount.

Mucus lines the inside of the nose. It also lines the lungs and the path that food takes. In the nose, it keeps things moist. Think of it as a thin, wet coat. It covers the inside of the body, where air and food go.

Hairs inside the nostrils help block bigger bits of dirt. Mucus catches dust and germs. That way, they stay out of the lungs. Then it drips down the back of the throat, carrying what it caught. We swallow it. Stomach acid helps destroy the bad stuff.

Tiny hair-like strands called cilia wave back and forth all the time. They sweep it, with the stuff it has caught, toward the throat. Think of them as a tiny broom that never stops. That is how the nose keeps the dust moving along, day after day.

A booger is dried mucus mixed with bits of dust, pollen and dirt. Blowing your nose into a tissue is a good way to clear out boogers, and it traps germs. Picking can make the nose bleed, and boogers contain lots of germs. So a tissue is a better tool for the job.

Some days the nose runs or gets blocked. That is a main sign of a cold. A cold usually gets better on its own in about one to two weeks. Many days may pass, but the cold does go away, and the nose goes back to its job.

Colds are spread by germs from coughs and sneezes, which can land on hands and surfaces. Washing hands helps stop colds from spreading. Use soap, and wash for about 20 seconds. Count slowly if you want to be sure, and your hands will be clean.

Words to know

• mucus: nose slime
• cilia: tiny hairs
• sinuses: nose air spaces
• acid: sour stuff
• tissue: nose wipe paper