So I've been shooting meth and heroin about 5 years now after smoking heroin for 7nor 8 years. I'm pretty sure this started after I started mainly shooting mixed shots of meth and heroin. When I do a shot which is a part hit and part miss and the needle is pretty close to the surface as its a surface vein usually, my skin in that immediate area turns blackish and a sort of blister forms that pops into a wound which eventually turns into a very dark scab that takes like a month to heal. What the fuck is this and why is it happening. It always ends up as a pretty deep scar but I almost never get an absess there either. Just the scab. At first i thought it was tar heroin causing it maybe but then it happened when i used china white too so now im fairly sure its the meth. My only guess is that the meth is missing just a bit bit close to the skin and it is so toxic to our bodies that it nectotizes the immediate area. Am i right or is it something else? Also any links on long term effects of iv meth use?