buying vitamin b12 injections B-12 Injection - Mobile and Clinic IV Therapy — ASAP IVs 6 and folate may be linked to depression.” Studies may be inconclusive Vitamin B12 Injections (Cyanocobalamin Injections)
Description
[1] [3] These injections are prescription-only medicines (POMs) typically prescribed by GPs for patients with confirmed B12 deficiency

for more details, see Sampson et al., 2021 13
It would then stop and go all day

It's not a magic solution

For info: In the FDA report published in December, the most common side effects were pain at injection site (91.6% of patients), fatigue (68.5%), headache (63.0%), muscle pain (59.6%), joint pain (44.8%), and chills (43.4%)

It belongs to the quinoline family, a class of small aromatic ring compounds, and sits far closer in size to caffeine than to insulin
