Are Vitamin B12 Shots Right for You? Low energy, brain fog, or feeling off? Vitamin B12 could be the missing piece. B12 supports energy, metabolism, and nervous system health, and injections provide optimal absorption for those who need B12 Shots vs. Oral Supplements: Which Is More Effective? Vital Force IV Therapy How Quickly Do Vitamin B12 Injections Work? Prime Aesthetics The Advantages of B12 Injections Versus Oral Supplements: Shawn Veiseh, M.D.: Family Medicine B12 injections often make a huge difference even though B12 taken orally is absorbed.