How often should vitamin B12 injections be administered and how frequently should laboratory monitoring be performed? Vitamin B12 Injection, 50 ml at 35 vial in Surat ID: 2851203786073 Vitamin B12 Deficiency: Recognition and Management AFP A simple Vitamin B12 injection can trigger a life threatening drop in potassium, Why Does This Happen?, Patients with severe Vitamin B12 Deficiency often have ineffective red blood cell production.