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, How Quickly Does B12 Shot Work? Duration of Benefits Vitamin B 12 intramuscular injections are also used therapeutically to help restore energy and combat various symptoms related to such deficiencies. Vitamin B 12 is essential to the development of healthy blood cells, nerve Vitamin B12 shots: Uses, benefits, and side effects Vitamin B12 Deficiency Harvard Health