Why does your mucus go green/yellow when you have a cold?

Answer 1

Your nose is inhabited by bacteria. Some of it is coloured blue and some of it is coloured yellow. They breed to form a defence when your nose in under attack so if you have green snot it's because the bacteria are breeding in equal measures.

Answer 2

Actually if your mucus turns green or yellow you have more then a cold and need to see a doctor. This is a sign of an infection and will most likely require an antibiotic.

Answer 3

So called "green" or "yellow" snot is the result of your body trying to get rid of a viral infection. When you get a "cold" you have a virus. Your mucus membranes produce "snot" to help wash out the infection. "Green" or "yellow" snot is also called purulent rhinitis by doctors.

Answer 4

CW was right!

Many of the common bacteria associated with humans are coloured, Staphylococcus aureus is a golden yellow, for example, and Pseudomonas pyocyanea (to give it its older, but more explicit name) is a shade of blue. Thus the green comes from the mixture of yellow and blue flora!
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Answer 5

green mucus indicates an infection.

Answer 6

if is yellow in colour is sign of infection