Methylcobalamin is a derivative of vitamin B12, which has the effect of nourishing and repairing nerves. 14-28 days is generally a course of treatment, and maintenance treatment takes about 3 months. How long it takes to restore the nerves depends on the individual, and it is impossible to make a generalization. Methylcobalamin is an important raw material for the synthesis of peripheral nerve myelin, and can be used clinically to treat peripheral neuropathies, such as idiopathic facial neuritis, carpal tunnel syndrome, trigeminal neuralgia, intercostal neuritis, ulnar nerve injury, radial nerve palsy, etc. Methylcobalamin is usually taken by intramuscular injection once a day first, and usually 14-28 days is a 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 continue to take methylcobalamin tablets to maintain the treatment for about 3 months. In addition, while patients take methylcobalamin, it is generally recommended to supplement vitamin B1 at the same time, which can better exert the therapeutic effect of the drug.