Excess mucus draining down the back of the throat may be caused by a cold, the flu, allergies, a sinus infection or certain medications, according to WebMD. A small amount of mucus is always present in the throat, but conditions such as these cause mucus volume to increase.
The process by which excessive mucus drains down the back of the throat is known as postnasal drip, according to WebMD. Postnasal drip causes the uncomfortable feeling of always having to clear the throat. The constant flow of mucus also leads to irritation of the sensitive tissues of the throat and can trigger a cough that often becomes worse at night. If the mucus flowing down the throat plugs the tube that connects the throat to the middle ear, an ear infection can develop.
The ideal treatment for postnasal drip depends on its cause, explains WebMD. If the excessive mucus production is brought on by a bacterial infection, treatment with antibiotics may help clear it. Postnasal drip caused by a viral infection, such as the common cold, can be treated with decongestant medications. Patients are also advised to treat postnasal drip by drinking more water, which thins the mucus and helps prevent it from blocking the passages to the ears. Using saline sprays or turning on a vaporizer may also help ease mucus accumulation in the throat.