I Have Been Taking Effexor For About 16 Months For

I have been taking Effexor for about 16 months for hot flashes. I had breast cancer (HER2) and take anastrozole. I want to get off the Effexor because I don't like the flat effect it gives me. My Dr. Recommended half the capsule for a month then stop taking Effexor. I feel dizzy and wonder how long this will last. Thank you.