FatallyFlawed - if you are getting depressed and self harming then you might not be ready to come off the venlafaxine?
In terms of how long it lasts this is how it worked for me.
75 MR -> 2x37.5/day 1am/1pm - nausea, disorientation, sleeplessness, faint 'zaps' duration:11 days
after another two weeks I made the following change:
2x37.5 -> 37.5am - same as above but much worse in the evening duration so far: 7 days
Therefore for me it was roughly around 2 weeks for 90% symptoms to disappear then maybe another two weeks for the remaining. So far after 7 days I still feel pretty crappy. I'm hoping after the next 7 days I'll feel better.
Anyhow good luck.