Some antidepressants may change the way the body processes tamoxifen, as was reported in the Journal of the National Cancer Institute (Vol. 97, No. 1:30-39). The effect may be especially great in 10 % of women with a particular type of gene variation. Effexor is one alternaitve new antidepressant that does nto interact in this fashion.
The authors of this small study caution that it’s too soon to know whether these interactions make tamoxifen less effective against breast cancer. However, it is also their conclusion that it may be premature to recommend routine genetic testing for the mutations identified in the study.