Phlegm in the back of the throat is often a symptom of an underlying condition. The most common causes of phlegm in the back of the throat include post nasal drip, gastroesophageal reflux disease (GERD), and environmental exposure.
Post nasal drip is a condition with excessive mucus production by the nasal mucosa which accumulates in the back of the nose or the throat. Patients often report symptoms such as constant swallowing, frequent spitting, difficulty breathing, and coughing. Post nasal drip is often caused by allergic rhinitis but it can also be caused by sinusitis or GERD. Treatment includes antihistamines for allergic rhinitis, antibiotics for sinusitis, and proton pump inhibitors for GERD.
GERD, also known as acid reflux, is a disease characterized by constant reflux of stomach acid into the esophagus. Patients often report symptoms of heartburn, sour taste at the back of the mouth, difficulty swallowing, excessive phlegm, or excessive salivation. Symptoms are often exacerbated by reclining or at night when sleeping. Treatment often includes medication that reducing acid production in the stomach thereby decreasing the amount refluxed.
Lastly, environmental exposure can cause excessive phlegm production. Smoking or second hand smoke is one of the most common cause of phlegm. Other irritants or allergens such as pollen, mold, fumes, pet dander, etc. can also cause an increased production in phlegm. Treatment involves identifying and eliminating the source.
In your case, the likely culprits from your excessive phlegm include allergic rhinitis, chronic sinusitis, gastric reflux, or an environmental exposure. An evaluation by your doctor to identify possible causes of your phlegm production would include a physical exam and careful history. If appropriate, antibiotics to treat an underlying infection, antihistamines to treat post nasal drip, or a trial of proton pump inhibitors to treat GERD might be indicated.