I have been injecting sub-Q for over a year and recently switched to IM per manufacturers recommendation. I have been rotating bicep areas and for the first time hit a vein in my lower bicep. Was the shot waisted? I don't know if I unloaded in the vein, or through it. I suspect through it, because I had the 3/4" needle in all the way and the vein was a surface vein, so I probably punctured both sides.