Injectable B12 Without a Prescription: 4 Big Dangers 003125 Henry Schein Medical 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 Now offering B12 injections! If these symptoms sound all too familiar, it might be time to check your vitamin levels. B12 injections may be absorbed up to 90% more effectively than oral Best Vitamin B12 Supplements Pharmacist Ranked U.S. News Vitamin B12 Dosages: Your GoodRx Guide GoodRx