Laura Martin, MD, MPH If it's a viral infection causing the yellow or green snot, yellow in particular is very common with viral cold infections. Antibiotics are really not useful for that.

Allergies and the very early stages of a viral infection ... as your immune system starts mobilizing against invaders. Yellow mucus indicates your immune system is actively fighting off an infection.

After they’ve done their job and die, they’re flushed out of your body with your mucus, and in the process can dye it yellow. Yellow mucus doesn’t mean that you need antibiotics, but it ...

Mucus is produced by the tissues lining our nasal passages. Often perceived as a mere nuisance, mucus serves a very important role. It acts as a protective barrier, trapping dust, bacteria, viruses ...