How do you get rid of scars from shooting up?

Answer 1

You'll need some plastic surgery --- nothing too extensive. Recently, in urban areas (LA for certain, but others exist) there are doctor's outreach groups that specialize in the removal of gang signs (tatoos, brands, etc.). As they're using the plastic-surgical techniques you'll need to remove that scar tissue, and as they list in their mission statement the desire to help people improving their lives to leave stigma behind, these might be a perfect solution for you.

Answer 2

You probably realize that shooting up is a much bigger health issue than having a bruise. There is not really any instant way to get rid of a bruise. Do not rub it, as that can both make it worse and be dangerous. For the first 48 hours, you can apply cold packs. After 48 hours, switch to warm packs. You can always camoflauge it with a little makeup as well, if you need to cover it for work or other things that can bring you more trouble. While you are waiting on that to heal, seriously consider that the bruise may be the least of what you are doing to your body. Talk to someone, like your doctor, about getting some help.