Vitamin B12 Deficiency: Vitamin B12 deficiency is a nutritional or absorption related disorder leading to impaired DNA synthesis and neurologic dysfunction, commonly presenting with megaloblastic anemia and neuropsychiatric symptoms. Physiological B12 Injection Frequency: How Often Should You Get a B12 Shot? Liv Hospital If I took vitamin B12 injections and folic acid along with magnesium, a B complex, and carnitine, but there was no improvement and my condition actually worsened with increased anxiety, does this mean Always Tired? B12 Injections Could Help