What Your Snot Says About You (Infographic)
Get the world’s most fascinating discoveries delivered straight to your inbox.
You are now subscribed
Your newsletter sign-up was successful
Want to add more newsletters?
Delivered Daily
Daily Newsletter
Sign up for the latest discoveries, groundbreaking research and fascinating breakthroughs that impact you and the wider world direct to your inbox.
Once a week
Life's Little Mysteries
Feed your curiosity with an exclusive mystery every week, solved with science and delivered direct to your inbox before it's seen anywhere else.
Once a week
How It Works
Sign up to our free science & technology newsletter for your weekly fix of fascinating articles, quick quizzes, amazing images, and more
Delivered daily
Space.com Newsletter
Breaking space news, the latest updates on rocket launches, skywatching events and more!
Once a month
Watch This Space
Sign up to our monthly entertainment newsletter to keep up with all our coverage of the latest sci-fi and space movies, tv shows, games and books.
Once a week
Night Sky This Week
Discover this week's must-see night sky events, moon phases, and stunning astrophotos. Sign up for our skywatching newsletter and explore the universe with us!
Join the club
Get full access to premium articles, exclusive features and a growing list of member rewards.
The paranasal sinuses are air-filled cavities that are lined with mucus-making cells. The mucus serves to keep the nose from drying out and to trap contaminants before they reach the lungs.
Mucus (”snot”) is made of water, proteins, antibodies and salts. Its color is an indicator of health:
CLEAR indicates healthy.
WHITE is thick mucus indicating sinus congestion.
Get the world’s most fascinating discoveries delivered straight to your inbox.
YELLOW means that infection-fighting cells are battling a cold.
GREEN indicates that your immune system is fighting a bacterial infection.
RED is blood in the mucus, possibly from broken tissue in the nose.
BROWN could be blood or an inhaled contaminant.
BLACK, unless you're a smoker, could mean a fungal infection.

