Vit B12 INJECTIONS vs B12 Tablets ? Name Dose & Duration of B12 Tablets Dr Rupal Explains Taking Vitamin B12? Read this first. While B12 is often hailed as a safe energy and brain booster, many real users are reporting unexpected side effects including anxiety, insomnia, Vitamin B12 Injections vs. Oral Supplements: Which is Better? Uniq Laser A vitamin B12 injection is a shot that delivers B12 directly into your muscle, helping your body absorb it quickly (especially if your body struggles to absorb it from food or tablets)