Serum vitamin B12 refers to the amount of vitamin B12 in the blood serum, which is an experimentally determined value, and there is no such thing as taking it. Can be taken generally is vitamin b12, is a cobalamin, common dosage form for injection and tablets, mainly used in megaloblastic anemia and pernicious anemia treatment, the specific use of dosage need to be judged by the doctor according to the patient’s condition. The main use of vitamin B12 tablets is oral, for the treatment of megaloblastic anemia, in the first 48 hours, need to closely monitor the blood potassium, in order to prevent the occurrence of hypokalemia. It is contraindicated in patients who are allergic to vitamin B12 or who have previously experienced allergic symptoms such as eye congestion and swelling due to eye medication, as well as in patients with gout, who may experience hyperuricemia with the use of this drug, which should be used with caution or under the strict guidance of a physician. When it comes to medication, it should be used in strict compliance with the doctor’s instructions, and it is recommended that patients consult a doctor for diagnosis before taking the drug, so that the doctor can formulate the exact course of treatment and dosage according to their own condition and physical condition, and do not use the drug blindly and privately.