Hello there, Ive been doing this for 4 years now and had some bad bleedings at times, but so far i havent had any permanent damage. Sometimes skin gets rubbed off and it takes a week to recover. Other than this can't really say that i have taken damage. You get also addicted to the pain if you in to it. I would like to go harder as well but there would be propably real damage than. But it is indeed very tempting to see where the borders are. Hope I could help you.