Tiredness and Vitamin B12 Deficiency: Symptoms, Diagnosis & Treatment Bolt Pharmacy Last year I got a diagnosis I'd never even heard of before: pernicious anemia. It explained the exhaustion, brain fog, and why am I this tired? days. Now it's monthly B12 injections Did you know all the great health benefits a Vitamin B12 injection can provide? It can also help you feel better in 24hrs #b12injections #vitamin #Vitaminb12 #Clinic #HurstTX How Quickly Does B12 Shot Work? Duration of Benefits