give b12 injection how to im injections livestrong.com Vitamin is essential for DNA synthesis, red blood How to Self-Inject Vitamin B12

[20] Treatment of megaloblastic anemia with concurrent vitamin B 12 deficiency using B 12 vitamers (including cyanocobalamin), creates the possibility of hypokalemia due to increased erythropoiesis (red blood cell production) and consequent cellular uptake of potassium upon anemia resolution

Lancet

For more in depth information on potential side effects, read this article from WebMD

But for most individuals, its puzzling to understand precisely how long it takes before they notice a difference once they begin B12 supplements or injections

Only a medical professional can conclusively determine if you have a vitamin B12 deficiency

Consult a qualified healthcare professional before starting any protocol