So thats the background biology
Some studies have shown that cyanocobalamin may be better absorbed by the body than methylcobalamin, although the science on that topic is currently mixed
Always good to have a reason I have also had this happen when my folate was low , it may be worth you getting it checked I had self inject my B12 every 4 weeks for the last 20+ (cannot really remember how long accurately), and 2 months ago got a similar 'electric shock tingling' all over my body - head, face, arms, hands, legs, feet etc within a couple of minutes of injecting, which lasted about 3 seconds or so
Vitamin B12 status is typically assessed by measurements of serum or plasma vitamin B12 levels
Anyone considering BPC-157 must understand they are exploring a research-stage compound with limited human safety data, not a proven medical treatment
Always patch test new products, but Copper Peptides are often a soothing alternative for reactive complexions.