Post-nasal drip is a common and often annoying symptom that many people notice at the very start of an illness. It can feel like mucus dripping down the back of the throat, leading to frequent throat clearing or coughing. In many cases, post-nasal drip can be an early sign of a cold or the flu, though it can also occur on its own or with other conditions. For same-day general illness treatment, visit the walk-in ...