Straight from the AME's mouth (just had a Class 2 exam).
Pilots shouldn't fly having taken Pseudofed (as PeterBruh said). However, it works its way out of the body quickly - which is why you have to take it every 8 hours - and so it is fine to stop taking it 12 hours or so before flying.
FWIW, he suggested Otrovine, but said that you shouldn't use it for more than about a week at a time.