I take effexor XR 150 mg. I got tired at first and then it went away. When I went up from 75mg to 150 I had to take 75mg in the morning and 75mg at night to keep from getting too tired. Now I take 150 mg at night and I'm fine. So it does get better. I noticed a difference the next day after I started taking effexor. I thought it would take a few weeks also. It sounds like it's going to work for you!