b12 injections not being absorbed Vitamin Injections: Hot Shots? Full Guide · PA Relief What You Need to Know

Preclinical studies showed lipolytic and anti-lipogenic effects, but human trials failed to demonstrate significant weight-loss outcomes

However, if you do find yourself deficient in vitamin B12, there is something you can do to improve it

boulardii intervention reduced the concentration of protein carbonyls in liver tissue, increased the activities of superoxide dismutase and glutathione peroxidase, and alleviated hepatic oxidative stress damage in this model [81]

That should give you a better understanding of what causes B12 side effects

B12 injections can be mildly painful for some however most patients can tolerate the discomfort well