I often see "mucus" and "mucous" used incorrectly, so I thought I'd try to explain the difference here. (Yes, I'm a geek...)

Mucus - Noun - A viscous, slimy mixture of mucins, water, electrolytes, epithelial cells, and leukocytes that is secreted by glands lining the nasal, esphageal, and other body cavities and serves to primarily protect and lubricate surfaces. Example: Whenever I'm around cats, my nose produces more mucus.

Mucous - Adjective - pertaining to, consisting of, or resembling mucus. Example: During cold, dry months, I often use Ayr Saline Mist to rehydrate the mucous membrane in my nose.

Mucosa - Noun - another term for mucous membrane; a membrane lining all body passages that communicate with the air, such as the respiratory and alimentary tracts, and having cells and associated glands that secrete mucus. The plural is "mucosae." Example: Pollen makes my nasal mucosa feel itchy.

(Thanks, dictionary.com!)

Depsite its bad reputation, mucus plays an important role within your immune system. It traps inhaled particles like allergens. However, the production of too much mucus is unpleasant.

Mucinex is an OTC medication that loosens and thins out mucus to relieve nasal and chest congestion.