When coughing with yellow sputum in the trachea, in Western medicine, it is usually inflammation in the trachea or lungs, and this inflammatory sputum is usually purulent or colored, which is drained from the inside out, that is, the inflammation is trying to drain out these inflammatory substances to promote its own recovery. In Chinese medicine, coughing with yellow phlegm is usually definitely a case of heat, which is actually similar to some bacterial inflammation in Western medicine, and is actually a category that covers each other. In Chinese medicine, if yellow phlegm is found, it is definitely necessary to clear lung heat, which is the same as western medicine’s anti-inflammatory drugs to help drain phlegm, and many of the Chinese medicine’s drugs to clear lung heat actually aim to clear lung heat, that is, to make the inflammation stop, and the inflammation will naturally stop after there is no heat. So when there is yellow phlegm, there is inflammation inside, and the yellow phlegm needs to be expelled.