How to Give B12 Injections at Home to Yourself PA Relief Vitamin B12 is essential for energy production, nervous system function, and red blood cell formation. However, oral B12 supplementation doesn't work well for everyoneabsorption can be limited by digestive issues, certain medications, How Quickly Does a B12 Shot Work? What to Expect B12 Injections for Energy: Benefits and How It Works AZ IV Medics GoTox RevIVe Ever wonder how fast you'll feel that B12 kick in? After an IM B12 injection, most people feel results in 1248 hours sometimes even Instagram Vitamin B12 shots: Uses, benefits, and side effects