The syndrome or pseudo-syndrome of post-nasal drip (PNDS) represents a diagnostic label which is unhelpful in the understanding of chronic cough. There is no accepted definition of PNDS and no accepted method of measurement. The symptom of mucus dripping down the back of the throat occurs in normal subjects and is also reported by many patients in ENT clinics who do not have a cough. The lack of any clear pathological or biochemical tests makes the syndrome both a catch-all and a dustbin.