Not Studied Yet
There has been very little in the dermatology literature regarding using herbal hormones for acne. I am assuming you are referring to the use of phytoestrogens for this purpose.
Estrogens in general help acne since they use up some of the sex binding globulin. This leads to decreased activation of testosterone. Estrogen itself also causes decreased oil production of the sebaceous glands.
There are many phytoestrogens in soy isoflavones. Lessers, but still abundant amounts,...