How Quickly Does B12 Shot Work? Duration of Benefits Vitamin B12 Deficiency Vitamin B12 deficiency happens when the body does not have enough vitamin B12. Vitamin B12 is important for making healthy red blood cells and keeping nerves Replying to @Angela Vitamin B12 supplements can trigger an acne like eruption, as can vitamin B6 & biotin supplements. In contrast to acne, there are no comedones. Once the supplements are stopped, Does B12 shots cause prominent vei Pernicious Anaemi How to Give a B12 Injection: Step By Step Instructions