Cough
Phlegm [2] is a type of mucus that your chest creates. If you are suffering from a cold or have other underlying illness, you usually create noticeable quantities of phlegm. When phlegm is coughed out, it is referred to as sputum. In the case of bacterial pneumonia, sputum, can be dry or wet. Sputum can be watery and in the form of pus. The mucus is often yellowish or greenish, with advanced pneumonia. In some cases mucus and phlegm can be filled with blood. Seeing yellow or green sputum is often a warning that your body is battling an infection. The colors are due to the white blood cells [3] in the blood. You might see yellow phlegm at first, which then develops into green phlegm. The change takes place depending on the magnitude and duration of pneumonia.