The symptoms of dizziness after patients take methylcobalamin are not related to methylcobalamin, which is an endogenous vitamin B12 and is widely present in the bone marrow blood system of patients. The adverse effects of methylcobalamin are mainly in the gastrointestinal tract, which may cause patients to have nausea, vomiting and diarrhea. Very rarely, it will cause patients to have allergic reactions, such as rashes, and will not cause patients to have neurological side effects, such as dizziness. Therefore, if a patient gets dizzy after taking methylcobalamin, consider that it is caused by other reasons. For example, whether it is caused by elevated blood pressure or insufficient blood supply to the brain, hypoglycemia, or heart disease, which causes cardiogenic cerebral blood supply deficiency. If the patient’s dizziness is heavy, it is recommended to consult a hospital and improve the relevant examination to clarify the cause of the disease, without considering that it is related to methylcobalamin.