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 Arm Numbness Causes and Treatment B12 Injections Explained by a Midwife Your body needs vitamin B12 to keep blood cells healthy and to make your nerves work right. But what happens when you run low? Here are some signs: https: wb.md 3PSgQRg Understanding B12 Deficiency: Signs on Hands and Feet