how often should i inject b12 Vitamin B12: Frequently Get It? Vitamin B12 Injections: Hot Shots?
Description
Once the needle shaft is in your belly, pull it back slightly to see if there is any blood at the point of insertion

Can it cause any serious side effects

Avoid touching the needle to the glass bottom of the vial, as this might dull its sharpness
The value of another blood test, holotranscobalamin (HoloTC), decreases with vitamin B12 deficiency

Always talk to a healthcare provider if you have concerns
