Hi I bought the B12 injectable liquid but there's no use by date on it or how long you have to use it once it's opened. Anyone know the answer? TIA x Compounded Vitamin B Complex Injection Empower Pharmacy B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics Are expired vitamin b12 syringes still effective? What Happens If You Inject B12 Wrong: 6 Red Flags