I am switching from Lexapro to Pristiq with my Pdoc. He recommended that I drop from my regular 20 mg of lexapro to 10mg and go to 50mg of pristiq. He said after 2 weeks drop the lexapro altogether. is this safe? is it too fast? I take 2 10mg tablets. Should I maybe go to 15mg--10mg-5mg-0? How have other people made the transition with minimum problems?