Why Do I Feel Worse After My B12 Injection? Causes & Management Bolt Pharmacy Vitamin B12 Injections: Good or Bad? 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 B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics Vitamin B12 Overdose: How Much Is Too Much? Dr. Axe B12 Injection Dosage and Frequency: 7 Essential Guidelines for Adults Liv Hospital