Personally I have practiced shooting left handed (predominately right handed) just to give my main arm a break. Although I have about 7-8 injection sites that I rotate from, it is a nice reassurance that I can shoot left handed if needed. I am also meticulously cautions when IVing drugs for reasons posted above. (Being in front of family, or a professional setting). Using micron filters,sterile saline, alcohol swabs, 29-30g syringes (one time use only), and triple antibiotic ointment basically leaves me without a mark within 15-30 minutes. I totally understand how bad you may want your fix but please take the extra 5 minutes preparing everything in a safe and cautious manner. By doing that alone you are exponentially reducing your risk of infections or damage. So what, it takes you an extra 5 minutes of prep... it's not like the shit doesn't hit you in 8 seconds after you push it.