Patients suffering from Lieber’s disease, gout, neurological damage and vitamin B12 with folic acid deficiency should not blindly use vitamin B12. It is not recommended to take vitamin B12 at the same time when using antibiotic treatment, and avoid overdosing for the following reasons: 1. Lieber’s disease: that is, family hereditary retrobulbar optic neuritis, the clinical manifestation of which is optic nerve atrophy, which is very rare. The blood picture will show abnormally elevated indicators of vitamin B12, not to continue to use vitamin B12 for treatment, so as not to make the optic nerve further atrophy, aggravating the condition; 2, gout: gout patients taking vitamin B12 will accelerate the degradation of ribose, resulting in a rise in the concentration of uric acid in the blood, inducing the onset of gout, it is recommended to use caution; 3, nervous system damage: although vitamin B12 can repair the damaged damaged peripheral nerves, vitamin B12 should not be used when the diagnosis is not clear to avoid masking the clinical manifestations of subacute joint degeneration of the spinal cord. Patients are advised to seek medical treatment when symptoms such as symmetrical sensory abnormalities in the limbs, unstable walking, loss of joint position sensation, and difficulty walking in the dark appear, and not to blindly supplement vitamin B12 on their own; 4. Vitamin B12 with folic acid deficiency: Although the blood picture of patients with this disease will improve after treatment with vitamin B12, it will make the symptoms of folic acid deficiency difficult to detect, so folic acid should be supplemented at the same time. The patients with antibiotic therapy are contraindicated: antibiotics can affect the determination of vitamin B12 in the serum, and if the microbiological examination method is applied, false low values can occur. It is necessary to measure serum vitamin B12 before and after use; 6. Avoid overdose: overdose of vitamin B12 may cause edema, asthma, palpitation and generalized rash, etc. Overdose in patients with malignant tumors may lead to tumor cell growth causing tumor recurrence or metastasis, so vitamin B12 should not be taken in excess, and the specific dose should be taken under the guidance of a doctor. In addition, the application of vitamin B12 in the treatment of megaloblastic anemia may cause changes in the patient’s blood potassium, so more attention should be paid to the detection of blood potassium. When taking vitamin B12, the dosage should be determined under the guidance of a doctor, taking into account the patient’s condition. In addition, it is important to maintain a light diet while taking vitamin B12, not to eat spicy and stimulating foods, and to stop smoking and drinking.