Carleton-Nathan says yellow, green, red, pink or brown mucus is not an immediate cause for alarm. Even dark yellow snot does not usually warrant a trip to the doctor. “In general, darker color ...

Julia Calderone wrote an earlier version of this post.

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 ... mix with the mucus and turn brown. But brown mucus isn ...