Vitamin B12 Injections Dosage and Frequency IVBoost Optimal Vitamin B12 Dosage and Treating Deficiency Vitamin B12 for Injection Cyanocobalamin 1,000 mcg, 25 Box (Rx) Mountainside Medical Compounded Cyanocobalamin (Vitamin B12) Injection Empower A little insight to the importance of the b12 injections. My client hadn't been feeling well & had some bloods done with her GP. The results identified a severe deficiency in b12.