There are a variety of causes for the accumulation of phlegm in the throat, one of which involves problems with the tonsils, the areas of lymphoid tissue on either side of the back of the throat. The tonsils act as part of the body’s immune system and their job is to help prevent infections, particularly upper respiratory infections.

Occasionally, the tonsils themselves can become infected and tonsillitis can develop. This can be the result of a virus or bacteria in the throat. Sometimes people develop tonsil stones on the back of the tongue or throat. These are small whitish bumps that can burst and are caused by bacteria that accumulate in the pockets of the tonsils, often resulting in a sore throat, throat phlegm, earache, bad breath, and cough.

Many times, tonsil stones can be treated by squeezing them with a cotton swab or using pulsing jets of water to remove them. In more severe cases, the tonsils themselves can be surgically removed in a relatively routine procedure.

Throat phlegm, or mucus, is produced by the cells that line the nasal passage and its purpose is to trap tiny particles, such as dust, and prevent them from entering a person’s respiratory system. Normal phlegm is clear and thin, while green, yellow, or grayish mucus may indicate an infection as a result of bacteria that have become trapped in the throat. Excess phlegm in the throat can lead to difficulty breathing or swallowing, coughing, and a sore throat, so a general physical exam is recommended.