Methylcobalamin can be taken for weeks, months, or even a year. The drug is a nerve-nourishing drug with fewer side effects and is mainly used to treat neurological dysfunction, such as peripheral nerve dysfunction, common clinical diseases by peripheral neuropathy, idiopathic facial nerve palsy, Grin-Barre syndrome, trigeminal neuralgia, and sciatica. Central nervous system lesions clinically common diseases, such as myelitis, spinal cord compression, subacute joint degeneration, brain lesions, such as cerebrovascular disease, cerebral hemorrhage, cerebral infarction patients, also seen in encephalitis, craniocerebral trauma, and craniocerebral tumors, patients with limb sensory disorders can be applied.