Methylcobalamin is a kind of neurological drug, which is mainly used in psychiatric and neurological diseases. If patients have neurotrophic deficiency or neurodegenerative changes, they can take methylcobalamin for active treatment. Methylcobalamin has certain damage to liver and kidney function, but it has less impact on liver and kidney function when taken within a short period of time, or has less impact on liver function if the patient does not have underlying liver disease; however, for some patients with viral hepatitis, long-term use of methylcobalamin may damage liver and kidney function, especially liver function, and even cause the possibility of liver insufficiency or liver failure. For patients who take the drug for a long time, it is recommended that the duration of taking methylcobalamin should not exceed 3-4 weeks in a row. If patients continue to take it after 1 month, it is recommended that they should stop taking the drug for 1-2 weeks and then consider taking further drugs for active treatment. In addition, if the patient takes the drug for a long time, the patient’s liver function should be checked regularly to see whether the patient’s liver function is normal, and if there is an elevation of glutamic acid and glutamic oxalacetic transaminase, it is necessary to consider stopping the drug for active observation.