The causes of phlegm in the mouth are often related to allergies and sinus infections. Most of the time, phlegm makes its way into the mouth from the chest and throat because phlegm in the mouth is almost always coughed up from these areas. In most cases, excess phlegm will go away when the root cause is gone. When allergies abate or cold and sinus problems rectify themselves, the amount of phlegm a person coughs up will almost always lessen. People who smoke occasionally cough up lots of phlegm in the mornings, and many people who quit smoking have reported that the excess phlegm disappeared once they kicked the habit.
People who have allergies or cold and sinus problems might end up dealing with phlegm in their mouths. In most cases, phlegm develops inside the chest and lungs when a person has had problems with allergies or sinus infections for an extended period of time. The phlegm is often associated with an infection, and it may be green to brown in color. People who are coughing up phlegm for more than a week may need to see their doctors so the possibility of infection can be ruled out. If a person has been coughing up a lot of phlegm over an extended period of time, he might have developed pneumonia or bronchitis, which the common cold and allergies can occasionally turn into.
Contrary to popular belief, phlegm and mucus are not exactly the same thing. Many people who experience phlegm in the mouth may believe it's just mucus when phlegm is actually the problem. It is often possible to tell the difference between phlegm and mucus by noticing the texture. Phlegm is usually much thicker than mucus and does not originate inside the nose or sinuses as mucus does. Mucus almost always runs out of the nose from the sinus area when a person has a cold or allergies, and phlegm is normally coughed up from the chest or inside the throat.
Coughing up lots of phlegm may be an annoyance for many people, but it is actually helpful. Getting rid of phlegm in the mouth is one way that the body gets rid of infection, and coughing up this excess means that the fluid that has settled into the chest and lung area is exiting the body. When fluid gets inside the lungs and chest and a person does not cough it up, there is a very good chance he will develop pneumonia, which can occasionally be a life-threatening problem.