Sputum, or phlegm, is generally considered good because it plays a vital role in protecting your lungs. However, its color, consistency, and quantity can indicate whether it's a sign of health or illness.
The Protective Role of Sputum
Sputum's primary function is as a protective barrier. As stated in multiple sources, it contains immune cells that fight off bacteria, fungi, and other foreign substances in your lungs and airways [1, 7, 8]. Its thickness helps trap these invaders, allowing cilia (tiny hairs) in your airways to move the sputum up and out of your body when you cough [1]. This natural process helps keep your respiratory system clean and healthy. [4, 7]. Mucus and phlegm, which are often used interchangeably, are a necessary part of maintaining lung health [3, 5, 8].
When Sputum Indicates a Problem
While sputum is usually beneficial, changes in its characteristics can signal a problem. A cough lasting longer than two weeks, or sputum that is yellow, green, brown, black, white, or red, warrants medical attention [2]. Changes in the color, thickness, or amount of sputum can indicate a respiratory infection or other health issue [3]. For example, green phlegm often signifies the body's fight against an infection [10], while different colors can indicate various infections [2]. Abnormal results from a sputum culture may indicate pneumonia, bronchitis, or tuberculosis [5]. The overproduction of mucin, the main component of sputum, can also be a cause for concern [6].
In Summary
The presence of sputum itself is generally beneficial for lung health. However, the quality and quantity of sputum are crucial indicators of respiratory health. Changes should be evaluated by a medical professional.
