Mean Plasma Concentration time profile of total vitamin B12 after Download Scientific Diagram 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 Delighted I received my B12. I don't see a use by date on them or am I missing it? Polymap Vitamin B Complex With Vitamin B12 Injection, 2 ml at 333 box in Nagpur Delighted I received my B12. I don't see a use by date on them or am I missing it?