administration of vitamin b12 injection Monthly Injection: Typical Dose & Schedule VITAMIN B12 INJECTION 3000 mcg

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

K.ParveenR.KandanS.JuluriS.et al (2017)

[1] Toxicity is extremely rare, though adverse reactions including hypersensitivity can occur, particularly with injectable forms

Current research shows that long-term use of B12 injections is safe for healthy individuals

May improve workout consistency: Better energy and reduced fatigue may make it easier to stay active, exercise regularly, and follow a weight management plan

Systemic subcutaneous injection (abdomen, thigh) distributes the compound via circulation, potentially benefiting follicles across the entire scalp