What color is phlegm in a cold versus the flu?

There's no typical difference in the color of phlegm between a cold and the flu. The color of phlegm can vary depending on several factors, including the stage of the illness, the individual's immune response, and any underlying health conditions.

Phlegm, also known as mucus, is a thick fluid produced by the respiratory tract. It helps protect the body by trapping dust, bacteria, and viruses. The color of phlegm can range from clear to white, yellow, green, or even brown.

In general, clear or white phlegm is usually associated with a mild cold or early-stage infection. As the infection progresses, the phlegm may become thicker and change color to yellow or green. This is due to the presence of increased immune cells, such as neutrophils, which contain a green pigment called myeloperoxidase.

However, it's worth noting that the color of phlegm is not a reliable indicator of the type or severity of an illness. Some people may experience different colored phlegm even with the same condition, and the color may also change over the course of an illness.

If you are concerned about the color of your phlegm or have other symptoms of illness, it is always best to consult a healthcare professional for evaluation and proper diagnosis.