injectable b12 how dispensed Injections: Who Should Get Them and Long Do They Last? Safe B12 Injection Guide at
Description
Narasimhan P, Sklar R, Murrell M, Swanson RA, Sharp FR

It has a variety of side effects that range from mild to moderate and sometimes serious

Vitamin B12 Injection IM Dose for Long-term Maintenance After the first treatment, shots are given less often

J Am Coll Nutr 1998;17:235-8

I often feel it wearing off about the end of day two...makes sense

And you dont have to worry about getting too much because its been reported that there are no reports of adverse effects associated with excess B12 intakebut thats not true