Produced by glandular cells in the airways, phlegm is of great importance for the defense of the organism, and its color can inform a lot about our health.

The phlegm , or nasal mucus, is produced by the glandular cells found in the airways, with the function of coating, filtering and protecting such a region of particles that can be harmful to it, such as dust and microorganisms. Thus, from a colorless substance, the mucus becomes darker and more dense, since it starts to contain these particles and also cellular debris.

The tissue that covers much of the respiratory system is rich in cilia . These structures help the displacement of thick mucus to the throat or to the outside of the nose, when more fluid is found.

In cases of infections, the microorganisms that cause it can go to the lungs, from where an even more consistent mucus is released. With the aid of eyelashes, it is directed to the throat and can be eliminated (if the person involved spills) or swallowed. In the latter case, the organism will reuse what is useful, such as proteins, polysaccharides and water responsible for the formation of mucus, and dispose of the rest along with the feces.

There are situations, however, in which the snot is more solidified, as a result of the dryness caused by the air we breathe. In such cases, it tends to remain there, in the nose, until it is removed mechanically. 


The color and texture of the phlegm can indicate whether something is not going well in your respiratory system. Thicker, white or greenish secretions may suggest viral infection ; and yellowish ones, bacterial infections . In the case of allergies , the color tends to be clearer and more fluid, but with considerably more mucus. In the case of dark colored phlegm, it may be an indication of bleeding, and it is necessary to seek medical help.

Leave a Comment