Does Vitamin B12 Injection Hurt Complete Guide by M.A.L 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 Signs You May Have a B12 Deficiency What Causes B12 Side Effects? YouTube I Feel Tired All the Time. Do I Need a B12 Shot?: Shawn Veiseh, M.D.: Family Medicine What Happens If You Inject B12 Wrong: 6 Red Flags