Methylcobalamin does not contain hormones. Methylcobalamin is an endogenous vitamin B12, which is widely found in the blood and bone marrow of human body. Vitamin B12 can help DNA synthesis and can promote the cellular myelin sheath of nerves for repair, so methylcobalamin also has the effect of repairing and nourishing nerves. In clinical practice, it can usually be used to treat peripheral nerve diseases, such as facial neuritis or peripheral nerve damage caused by diabetes, polyneuritis and acute inflammatory demyelinating polyneuropathy, which can be treated with methylcobalamin. The adverse effects of methylcobalamin are relatively few, but it should be noted that people who have been engaged in mercury and chemical industry for a long time need to be applied with caution and avoid long-term application. In clinical practice, patients who have peripheral nerve injury, manifesting as numbness and pain in the limbs, can take methylcobalamin orally.