You can click on my name, or anyone's name on this thread and read all their posts. I have quite a few, so I'll reprise my history.
I started taking 25mg Effexor in 2001 for hot flashes (an off-label use). My breast cancer was estrogen-driven so I was given tamoxifen–it binds up the estrogen in your body which put me into a chemically induced menopause.
In the Fall of 2014, I was diagnosed with a different breast cancer. I asked my oncologist if I should get off the Effexor as my treatment was going to more grueling and I probably didn't need it for hot flashes anymore, anyway. He told me to hold off–not to rock the boat right now.
I waited until the Spring of 2018 and tapered off by cutting my small flat tablets into tinier and tinier pieces. I took two months to get off 25mg. I was fine for about six weeks after the taper. Then, I began experiencing all the symptoms of Effexor withdrawal–anxiety, insomnia, agitation, shakes, akathisia, fear, dizziness, etc. I had been on Effexor for almost 18 years–I think six weeks is how long it took for my body to "use up" all the stores of this drug stored in my body tissues.