Methylcobalamin is a derivative of vitamin B12, which is easily absorbed by the human body. Its function is to nourish the nerves and to supplement the body as a raw material for hematopoiesis. Mecobalamin is mainly used for nerve injury, numbness of limbs and muscle atrophy, and it can also be taken orally by patients with peripheral facial neuritis, diabetic peripheral neuropathy and alcoholic peripheral neuropathy. The side effects of methylcobalamin are mainly gastrointestinal reactions, some patients have nausea and abdominal distension after taking it due to poor gastrointestinal function, most patients can tolerate it, and vitamin B12 can be considered for intolerant patients. it is recommended that patients take methylcobalamin orally under the guidance of physicians, and if it does not work for one month, it is recommended to switch to other drugs under the guidance of physicians.