What color is mucus?

First you get congestion and clear nasal drainage for the first couple of days.

Then during the middle the secretions start to take on some white and light yellow color due to the White blood cells that are moving in to the area to clear up the infection.

Then towards the tail end of the cold the secretions will start to get a little green tinge, often the 10 to 14th days. This is because of some enzymes, called myeloperoxidase that are produced by your immune system in the process ot clearing up the infection.

At this point your cold should be over. Our guidelines by the AAP recommend that we clinically make the diagnosis of sinusitis for a cold that hasn't started improving after 10 to 14 days. This being said, about 10% percent of colds will fall into that range of taking 14 days for resolution. So a little green at the tail end of a cold is fine, so long as you are not spiking a fever late in the course or developing pain in your face, is ok.