What Happens If You Inject B12 Wrong: 6 Red Flags Vitamin B12 (cobalamin) and folate (vitamin B9) are vitamins that serve important functions in the human body. Folate is needed for development and growth of cells (including red blood cells) and synthesis The Dangers of Vitamin B12 Overdose Vitamin B12 Overdose: How Much Is Too Much? Dr. Axe How Quickly Do Vitamin B12 Injections Work? Prime Aesthetics The Truth About B12 Injections: Benefits, Cost & How They Work