side effects of not having b12 injection What You Need to Know About Vitamin Vitamin B12 Deficiency - Harvard
Description
You only need a referral if you have a complex medical history

Metabolism and Excretion Metabolism AOD 9604 is partially degraded by protease in adipose tissue, generating inactive metabolites
NNMT : SAM (S-) , 1- (1-MNA)

It is extremely difficult to have too much B12 in your system

B12 injections, when administered as recommended, pose a low risk of overdose