Not at all! Many of our readers self-inject without problems. If you have some body fat, you'll barely feel anything. When you think of painful injections, what you have in mind is intramuscular (IM) shots, like most vaccinations. IM is indeed painful, although not as much as a lifetime of illness which could include paralysis, recurrent infections, hair loss, skin problems, and infertility. Anyway, B12 is highly effective when injected subcutaneously, so you don't need to do IM. SQ gives little to no pain, especially when the B12 is dissolved in saline. To get rid of the fear factor entirely, you can use a needle-free injection device.