I have been taking Pristiq for a month now but went up to 100mg in the last week. Since then I have not been able to go to the toilet (for want of a better word). The dr says I should take fiber and movical but it's not working. I was wondering if anyone else had this side effect on this anti-depressant and if it got any better. I'm wondering if I should just go onto something else rather even though it is working quite well for me.