A viral infection of your nose can cause "blood vessels and mucous membranes in the nose to swell, resulting in a runny and a stuffy nose," Dr. Damask says. While your mucus may look clear at first, in a few days, the nasal drainage typically starts to become thicker and green or ye...
A runny nose is characterized by excessive nasal discharge. Also known as rhinorrhea, it results from swelling or irritation in the nasal tissue, which can be due to various reasons. The discharge may range from a thin clear fluid to thick mucus, which runs out of the nose, down the throa...