I took Effexor for 2 years and I had a love hate relationship with the medication.  I loved the medication b/c it really did work..........I'd go as for to say it changed my life.  I hate the Effexor b/c the side effects were so bad.  While on the medicine I had vivid dreams, night sweats, dizziness, brain zaps, and absolutely no sex drive.  The worst of the side effects came in withdrawal when I stopped taking the medicine to become pregnant.  The half life (time the medicine takes to build up in your system) is very short.  Because of this you may suffer withdrawal/side effects from missing your dose even by hours.  The magic tip for me to stop the withdrawal from the Effexor was to take 10mg of Prozac for 2-4 months after finishing the Effexor.  The Prozac counter effects the Effexor withdrawal, so essentially you don't have to suffer any withdrawal when stopping Effexor as long as you follow it directly with the Prozac for a few months.  Prozac has very little to no withdrawal.