Post-nasal drip is a common symptom of colds, allergies, and infections. It is characterised by mucus from the nose or sinuses that continuously drips down the back of your throat, causing irritation.
Phlegm can build up at the back of your throat when you lie down in bed and trigger coughing at night ... says wet coughs can also be caused by chronic lung conditions such as chronic bronchitis ...
Accumulation of phlegm in the chest is a common problem during winter and changing weather. This problem not only causes difficulty in breathing but can also increase cough and sore throat.