I was on Effexor for several years for major depression, which I had from young adulthood. BOY did it help me!
BUT. I am a creature of habit and if I don't do my regular things, well, regularly, I forget. We had guests for a few days and I forgot my Effexor for 2 days. I ended up in the ER. Horrible symptoms. My doctor put me on a lower dose and I gradually weaned off of them. I DO mean gradually and it was brutal coming off that stuff.
After it was out of my system I sunk into a big time Depression again. Then I learned how vitamin D3 helped depression. I started taking it (10,000 units a day) and within 2 weeks my Depression was gone..... and it remains gone. Now I take 5,000 units in summer and 8,000 to 10,000 units in winter. It HAS TO BE D3, not regular vitamin D.
If you are out in the sun in summer, you would of course need less.
BTW, my daughter-in-law was on the dose you are taking and she had a really hard time getting off them too.
If you don't want to try the D3, maybe you can get your doctor to prescribe something different?