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 B12 Injections vs Supplements: 16 Key Facts Explained 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) Understanding The Benefits of B12 Shots for Weight Loss Low Vitamin B12? Diet vs. InjectionsWhat Works Faster?