Can post nasal drip cause reflux?

No, but. Sometimes the problem is not that producing too much mucus, but rather it's not being cleared away effectively. Swallowing problems can cause a buildup of liquids in throat, which can feel like postnasal drip. These problems can sometimes occur with age, a blockage, or conditions such as GERD. The conditions can coexist separately in the same patient. See ENT doc to sort out the problem.