If you are taking B12 on a regular basis and its absorbing into your body, this supplementation will raise the serum B12 levels
Mild injection site reactions, fatigue, headaches
For the 10 mg vials small 45 unit draw, use fine gradations for accuracy details in the insulin syringe units guide
FAQs: Is it possible to schedule all three services in a single visit
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