"i have been taking 50mg of pristiq for about 5 weeks now, and just started taking 100 mg a couple days ago. i am 31 yrs old, but have been on antidepressants for 10 yrs. i&#039;ve tried many ssri&#039;s (lexapro for several yrs) and never felt much better at all. i remained depressed and began to try to accept that this is just what my life would be. finally, about 2 months ago my drs office began doing genetic testing which can guide them on what medicines your body will respond best to. so pristiq it was. i think my mood has lifted somewhat. i&#039;m really hoping it will improve even more as studies show full benefits take 6-8 weeks. "