What is phlegm?

Phlegm is defined as mucus that originates from the lungs, and it is typically free from contamination by oral secretions. This is important because phlegm serves as a protective and cleansing element in the respiratory system, helping to trap and expel pathogens, irritants, and other debris that can affect lung health. The characterization of phlegm as being uncontaminated by oral secretions underlines its role as a vital component produced directly by the respiratory tract, distinguishing it from other forms of mucus that may be influenced or altered by the environment of the mouth or throat.

Understanding this distinction helps in diagnosing respiratory conditions, as the nature and characteristics of phlegm can provide critical insights into underlying health issues. For instance, variations in its color, consistency, and the presence of other components like pus or blood can indicate different types of infections or inflammation within the lungs.