Does taking evening primrose oil capsulesdaily cause side effects like reduced testosterone levels?

Lots of unknowns: Evening primrose is peddled as good for almost everything, which can't possibly be true; its proponents cherry-pick obscure journals and exaggerate the claims. The most believable claim is that it helps women who get sore breasts at the same time each month. It probably does not help with acne. I could find nothing on its reducing serum testosterone, but i'd still discourage you from using it.