Medically reviewed by Amelia MacIntyre, DO Mucus, a fluid in your upper respiratory system, is usually clear. But a number of health conditions can cause it to turn brown. Also known as brown phlegm ...

Ever notice that when your tears start flowing, no thanks to that sappy rom-com, your nose does, too?” Dr. Philip Chen, who is a professor of otolaryngology and rhinology at the University of Texas ...