From colorless to pink: Structural insights into vitamin B12 induced color change in monoclonal antibodies ScienceDirect Ever wonder why B12 shots are red? Here's the scoop! , B12 injections naturally have a deep red color due to the presence of the cobalt corrin complex, a key component of its molecular structure. Hydroxocobalamin acetate ampoules, vitamin B12a. Red coloured solution for injection in the treatment for vitamin B12 deficiency. Accord Healthcare Stock Photo Alamy Vitamin B12 Injection Hela Medical Spa 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