what color mucus indicates infection
Your mucus can also change color when you're sick. Green mucus is a sign that your bodyâs immune system is at work. The color comes from a type of infection-fighting white blood cell. âWith cold or flu, mucus starts clear, then begins to darken as it gets thicker, Kemmerly says.
On the other hand, green mucus is often an indication of a bacterial infection in the respiratory system, when accompanied by the following other symptoms: 1  nasal congestion. 2  high fever, especially when lasting more than 3 days. 3  sinus pain.  blood is present in the nasal discharge.