I take an Aromatase Inhibitor (AI) for stage one breast cancer. I could not tolerate the low estrogen and the brain fog so I take Zoloft and Vyvance which help. Still suffer from fatigue which is effecting my job performance. I now have an option to change to Tamoxifen instead of the AI but will then need to change my SSRI from Zoloft to Effexor. I am afraid of getting headaches and insomnia during the wean form Zoloft.