How Long Does A Vitamin B12 Shot Last NEW TREATMENT ALERT A vitamin B12 injection helps treat or prevent deficiency by delivering the vitamin directly into the bloodstream. It's often used for people with absorption issues and is usually safe Seeing Red: Do B12 Injections Work? LAmag Fun Fact Friday! Ever wondered Why is my B12 injection red? All B12s are cobalamins they have a cobalt atom at the center of a special ring shaped molecule called 24 Hour B12 Injections