why do you have vitamin b12 injections Best Injection Sites: Where to Inject B12 · PA Relief Best Vitamin B12 Injection Site:
Description
The AAFP advises that injectable therapy leads to more rapid improvement and should be considered in patients with severe deficiency or severe neurologic symptoms (Langan RC, Goodbred AJ, 2017)

In a human hair follicle organ culture model, AHK-Cu demonstrated three key effects at concentrations of 10^-12 to 10^-9 M (extremely low doses) (Pyo et al., Arch Pharm Res, 2007)

It works by calming down an enzyme (NNMT) that slows the metabolism in people with obesity, diabetes, or aging

A topical numbing cream can be applied prior to the injection if you need it
