How Long Does Paxil Take To Be Completely Out Of The System?

Hi there, my boyfriend is on Paxil and is looking to switch due to some side effects that he is having. His GP has suggested that he goes to a Psychiatrist as he is not comfortable playing with his meds. How long does it take to ween of of Paxil? The second question I have is what is the difference between and SSRI and Non SSRI?