It is worth noting that neurological symptoms can occur even in the absence of anaemia, meaning a normal full blood count does not rule out clinically significant B12 deficiency
Blood and lymphatic system disorders: anemia Gastrointestinal disorders: diarrhea General disorders and administration site conditions: pyrexia, injection site pain Metabolism and nutrition disorders: hypokalemia, hypomagnesemia, hypoalbuminemia, hypophosphatemia Musculoskeletal and connective tissue disorders: muscle spasm Nervous system disorders: headache Psychiatric disorders: agitation Renal and urinary disorders: oliguria Respiratory, thoracic and mediastinal disorders: atelectasis, pleural effusion, pulmonary edema, stridor, wheezing Vascular disorders: hypotension, hypertension Substances that induce or regulate hepatic cytochrome enzyme CYP2E1 may alter the metabolism of acetaminophen and increase its hepatotoxic potential
J Appl Biochem 5:4352 Hibi T, Nii H, Nakatsu T, Kimura A, Kato H, Hiratake J, Oda J (2004) Crystal structure of gamma-glutamylcysteine synthetase: insights into the mechanism of catalysis by a key enzyme for glutathione homeostasis
One of the most immediate things people notice is a natural increase in energy