5 Ways Lipotropic B12 Injections Help You In Weight Loss 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 Purpose of FitShot Injection HomeKit at VITAstir Clinic Vitamin Injections B12 Shots IV Therapy The Feline Essentials B12 has definitely improved my cat's appetite and appearance in recovering from Pancreatitis. I started using the B12 last week in combination with the CATalyst product that I've been Delighted I received my B12. I don't see a use by date on them or am I missing it?