If you have been researching hormone replacement therapy, you have probably run into two terms that sound medical but are rarely explained clearly: bioidentical and synthetic. Understanding bioidentical HRT vs synthetic HRT is one of the first and most important questions to work through before starting any hormone treatment. Both approaches are used to address the changes that come with perimenopause and menopause, including hot flashes, sleep disruption, mood shifts, and low energy. But they are not the same thing. They differ in how they are made, how they interact with the body, how they are regulated, and how they are prescribed.