why b12 injection is painful Does Vitamin Hurt Vitamin B12 Injections vs. Supplements:
Description
selective nicotinamide N-methyltransferase (NNMT) inhibitor Purity: 9899% (HPLC-verified, research grade) Appearance: Off-white to pale yellow crystalline powder (salt) or reddish-brown to orange powder depending on form or salt Physical Form: Lyophilized or crystalline solid powder

You will need a professional to guide you on administering the injection properly if you are starting this treatment

B12 does not stack: once your blood level is in the normal range, extra B12 is simply passed out in your urine rather than converted into more energy
The unresolved issue of the high-folatelow-vitamin B-12 interaction reemerged due to challenging but inconclusive findings from population studies in the postfortification era

Pharmacotherapy, 42(9), 659-667