The truth is they can cause your bone plates to fuse prematurely, therefore preventing you from becoming taller. This is only a problem in adolescence. After about age 21 or whenever you aren't growing taller anymore than it becomes safe to use. The estrogen that certain steroids aromatize to is what causes your plates to fuse and ultimately causes you to stop growing. In medical practice they do use anavar in children when needed for certain conditions without the fear of stunted growth, for the simple fact that oxandrolone doesn't aromatize to estrogen. I imagine halo and proviron would be O.K. too. That is the TRUTH.