I have GAD with associated depression, I took lexapro 5 mg for 2 months, then 10 mg for 1 month, then 15 mg for 1 month, and then 20 mg for 2 months now, but i don't feel much better, sleeplessness is another problem. I have taken desvenlafaxine 50 mg earlier for 9 months, which worked better. Now, if i want to go back to desvenlafaxine 50 mg, how should i go for it? directly replace lexapro 20 mg with desvenlafaxine 50 mg? or first taper of lexapro 20 mg,(how) then go for desvenlafaxine 50 mg?