giving a b12 injection Instruction Guide for Intramuscular (IM) Self-injection of Methylcobalamin 1mg/5mg Vitamin B12 Injections
Description
A never-ending bidirectional cross-talk
The injection provider can administer the B12 shot deep into the muscle (intramuscularly) or into the tissue layer between the skin and the muscle (subcutaneously)

H., Cant C., Wanders R

Deficiency can also be caused by poor absorption

However, it's still important to follow your prescribed dosagemore isn't necessarily better, and using only what you need is both medically appropriate and cost-effective
Nature 500 (7464), 541546
