Can I take stacker 2 or3 and use synex 12 hour nasal spray? Right now I take zyrtec for my sinus problem also.

No nasal decongestan. Be aware that over the counter nasal decongestant sprays are extremely addictive and should only be used for 3 days max. You can use zyrtec d or go to your doc and get a prescription for a steroid nasal sprays that is much better and is not habit forming.