Postnasal drip brought on by conditions such as allergies, colds and taking certain medications is one potential cause of frequent throat clearing, according to WebMD. Laryngopharyngeal reflux can also result in frequent throat clearing, as it causes stomach acid to enter the throat or voice box.
Mucus produced in the nose normally mixes with saliva and drips down the back of the throat unnoticed, notes WebMD. If the mucus is thicker than normal, or if the body produces more mucus than normal, the excess mucus moves from the nose to the throat in the form of postnasal drip. The feeling of excess fluid in the throat causes constant throat clearing, which may be accompanied by a cough, a sore throat and hoarseness. Allergies, colds, sinus infections, certain foods, and medications such as blood pressure medications and birth control pills may cause the production of excess or thick mucus.
Laryngopharyngeal reflux, or LPR, occurs when there is a malfunction of the sphincters that normally block stomach acids from entering the voice box or throat, causing frequent throat clearing, states WebMD. LPR is common in infants because their bodies are not fully developed and they spend much of their time lying down. Doctors do not know the cause of LPR in adults as of 2015. People with untreated LPR may suffer from scarring of the throat and voice box, increased cancer risks, and irritation of conditions such as asthma or bronchitis.