Experiencing any of these symptoms? B12 supplementation might be right for you. Some causes of low B12 are diet, alcohol use, certain diseases like Chrohn's and Celiac Disease, and Gastric Bypass surgery, B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics CYANOCOBALAMIN INJECTION, USP 30000 mcg 30 mL (1000 mcg mL) 30 mL VIAL Cyanocobalamin (B12) Injection 1000 mcg mL, Multiple Dose Vial 30 mL McGuff