I had a four year daily benzo/z-drug habit that I kicked in a detox in August 2014. The withdrawal from that was improving consistently but a little slow, but all the issues were largely physical after a month.
At five months off benzos, my issues were severe insomnia (up for days at a time) and lingering anxiety. This was making my new job difficult so I saw an outpatient psych (set up through my detox center) who suggested going on gabapentin for a few months to get over this hump. He assured me that it was safe, did not cause withdrawals, had no negative side effects, and wouldn't cause a taper.
I took it for seven weeks at doses of 1200mg - 2100mg per month, and while I was on it, it messed me up really bad. Depression, anger, and nasty physical issues during interdose withdrawal or when waiting for it to kick in. I stopped it cold turkey after a few ER visits and a five day inpatient stay (the symptoms were that nasty). That was one year ago.
I still suffer greatly with vicious physical symptoms (hair loss, heart palpitations, nerve pain, shakiness, alcohol & caffeine intolerance) and psychological symptoms (irrational fears, derealization, cognitive impairment, SEVERE anxiety, inability to drive). I have gone to many doctors about this and not one has yet been able to provide any help.
If you have the ability to do so, then taper slowly. Because the only thing worse than dealing with an endless withdrawal, is having every doctor not have a clue what is wrong with you while you're in that withdrawal.