why do people inject b12 Vitamin Injection Sites: All You Need to Know B12 Injection Dosage and Frequency:

While FAs are essential metabolic substrates used for cellular energy, in excess, FAs can have deleterious effects through the buildup of toxic lipid metabolites (8) in a condition known as lipotoxicity (9)

For patients with these conditions, a maintenance schedule of injections every one to three months is typical after getting their levels back up

2017;8:CD006612

I will not let my guard down though no matter what My state in the western USA (actually my county) is very particular who gets in line

Intramuscular injection may be clinically preferable to oral supplementation in specific situations: For individuals whose bloodwork shows deficiency or insufficiency in B12, vitamin D, or other measurable nutrients, and who have not achieved adequate levels through oral means