Maybe where's evidence meds balance things out?

I got my medication today, and when I looked at the prescription label, there was just a brief description of how it works. It doesn't mention anything about how well it will adapt to my specific body and mind or how it's supposed to create a balance for me or counteract any side effects from my condition. I'm wondering why doctors prescribe meds without more detailed information on these points? Maybe I'm missing something, but i feel like there should be more clarity or explanation about how this medicine is supposed to work specifically for me.