My doctor wants to change my prescription of 50mg. zoloft, which I have been taking for eight years, to 75mg. of EffexorXR. He was sidetracked before telling me how to switch from one to the other and I forgot to ask. Can I just start taking the Effexor immediately, or do I need to ween myself off of zoloft then begin the effexor? Any help would be greatly appreciated.