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 Blood thinner injection side effects? Vitamin B12 Injection Dose for Adults: 7 Essential Dosage Facts & Schedules Liv Hospital The Risks of An Incorrect Intramuscular Injection B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics Vitamin B12 shots: Uses, benefits, and side effects