Methylcobalamin is an essential nutrient and endogenous vitamin B12, which is used clinically for the treatment of peripheral neuropathy due to various reasons. If the symptoms improve after taking the drug, it can be taken for a long time according to the doctor’s prescription; if the symptoms do not improve after taking methylcobalamin for one month, it is necessary to stop using it and consult the doctor for follow-up, whether to continue taking it or to change the drug treatment. Methylcobalamin is involved in the synthesis of brain cells and spinal cord nerves in human body, and has the function of nourishing nerves and promoting the restoration of normal nerve functions, as well as promoting the utilization of folic acid and the synthesis of lecithin, and improving the maturation and division of red blood cells. At the same time, people who are exposed to mercury and its compounds in a high concentration environment for a long time should not take large amounts of methylcobalamin for a long time, so as to avoid the replacement of mercury inhaled by human body with ammonium ions in methylcobalamin and the generation of mercury ions, which may cause damage to human body and even mercury poisoning. In addition, pregnant women and nursing mothers should use methylcobalamin with caution, and it is recommended to use it under the guidance of professional doctors; elderly people may need to reduce the dosage appropriately to avoid increasing the metabolic burden of the kidneys due to the reduced metabolic ability of the body.