Methylcobalamin is a nerve-nourishing drug, which is mainly used clinically for the treatment of peripheral neuropathy and megaloblastic anemia. Its specific course of use is related to the primary disease treated. There are more indications for methylcobalamin to treat peripheral neuropathies, such as idiopathic facial neuritis, carpal tunnel syndrome, trigeminal neuralgia, intercostal neuritis, ulnar nerve injury, radial nerve palsy, etc. It is usually taken first by intramuscular injection, once a day, usually 14-28 days for 1 course of treatment. If there is no effect within 1 month, it is recommended to change the treatment plan in time. If there is an effect, it is recommended to switch to oral methylcobalamin tablets for maintenance treatment for 2-3 months after 1 month. In addition, if used for the treatment of megaloblastic anemia, it is also generally taken first by intramuscular injection once a day for 2 months as a course of treatment, followed by 2-3 months of maintenance treatment. However, if patients experience serious adverse reactions such as a drop in blood pressure and respiratory distress during the course of taking the drug, it is recommended that the drug be discontinued immediately and that appropriate measures be taken to the hospital for treatment.