What Harm Is There In Taking Hair Loss Medications If I’m Not Balding?

What are the side effects (Other than the ones easily available through literature) of taking something like propecia, rogaine, or saw palmetto when there isn’t any hair loss evident? What I mean is there any extra harm one can do to themselves if they choose to take one as a preventative measure?

As a matter of point, the side effects of taking nothing are less than taking something. Why take a medication that has no proven value for you as a young man? One can make an argument that Propecia can reduce the risks of prostate cancer, although it is not the reason used today to take it in a normal young man. It will not prevent hair loss if you do not have the gene for hair loss.