I had shots for years and when I switched to a new doctor they said it was an outdated idea that anyone under the age of 70 needs them. Along with other issues including a low Vitamin D, I have pernicious anemia..my body downtown readily absorb B12. I take the sublingual and although it doesn't raise the numbers to the levels I had with the shots, there is a big difference. Tablets and pills don't absorb into the blood stream at least in my case as well.