Benefits of Vitamin B12 Injections for Skin B12 Injection sites + How to use B12 Shots Safely If you have a low vitamin B12 level, injections can go a long way toward improving your health and well being. But if your B12 level is normal, don't fall for claims that Your B12 report should be >400. Here's why nobody told you. . Indian labs flag B12 as deficient only below 200 pg mL a cutoff designed decades ago to detect anemia,