All That Runs Green Is Not Infection

What is the clinical significance of green mucus?

— William J. Sciales, MD
Flushing, NY

To help lubricate the epithelial surface of the nose, mucus must move steadily toward the pharynx, where it is eventually swallowed. If it stagnates in the nasal or sinus cavities, it can dry out or become infected. Mucus that has dried out—as can occur in a wider-than-average nasal cavity—can turn yellow or green just as infected mucus usually does.

It is sometimes difficult to determine whether discolored mucus results from a viral or bacterial infection or merely from nasal cavity dryness. Saline lavage of the nasal cavities may clarify the cause of mucus discoloration and is therapeutic at the same time. If a patient has dry nasal cavities or stagnant mucus, saline lavage will alleviate the problem. If infection is present, lavage may help resolve it or at least ameliorate symptoms.

— Donald A. Leopold, MD
Professor and Chairman
Department of Otolaryngology—Head and Neck Surgery
University of Nebraska Medical Center
Omaha