I have been on it for years with no appreciable side effects. It worked really well for me for quite some time on its own, and it seems my illness got worse and I needed more. It is doing something still... I have come off of it twice and became markedly worse both times. As a result, we keep it as the foundation of my "med cocktail"- it is obviously still doing something. I definitely would give it positive reviews; it saved my life.