How to Self Inject Vitamin B12 at Home The Sanctuary Wellness Institute Lets do my first B12 injection together This is something Ive been nervous about for a long time, but today I finally did itand it honestly wasnt bad at all. I used the Union Medico needle guide Subcutaneous Injection: What It Is and How to Give One Methylcobalamin Injections Vitamin B12 The HCG Institute like, swipe, and save for when it's your turn to do an injection on a patient Intramuscular (IM) Angle: 90 Needle Size: 2225G, 11.5 inch Med Examples: Vaccines (e.g. Tdap, B12 Energy Shot The IM Shot Series