text: does postnasal drip cause bad breath? if what doctor can assist with this problem?   yes, postnasal drip can cause bad breath.   i would first recommend an over-the-counter saline solution or an antihistamine (if your postnasal drip is caused by allergies).   if this condition continues for a prolonged period, you should see a doctor. this could be a sign of a bacterial sinus infection. in this case, a doctor could easily prescribe antibiotics to alleviate the problem.