Intravenous injection is the fastest form of relief from discomfort or pain this is because when injected, the drug goes directly to the bloodstream where it begins to function. It takes few minutes for it to began to take effect.

The main reason while B12 is injected into the body rather than taken orally is because of absorbance. Injection absorbs faster into the blood stream where itg works more than pills.

Sending my warm regards and success in the engagement.