I have been on Effexor for about 4 years now. I also am on a high dosage 150 mg a day. It seems to work for me. I was on Celexa first, but after a week I was feeling SO SAD!!!! I called my doctor right away and she had me wean off of it.
The only side effect I seem to have experienced is horrible nightmares. Very vivid and frightening. That stopped after a month or so.
Baloo, take Chutz' advice. No matter what your daughter takes, keep an eye on her and make sure she knows it is important to let you know how she feels.