who can administer b12 injections How to self-inject intramuscular vitamin - Overview How to Self-Inject Vitamin B12
Description
If no problems occur, gradually increase to your target dose

Some people might experience side effects

Create a V shape with the fingers
According to the product label there is 250 mcg of Vitamin B-12 (cyanocobalamin) per 1 ml
Its not known to have any major side effects

Zhu, Y., Luo, M., Bai, X., Li, J., Nie, P., Li, B., & Luo, P
