Lysine refers to Lysine Hydrochloride, which has the effect of promoting human development, improving the function of central nervous tissue and enhancing the immune function. Lysine is one of the essential amino acids in human body, which can promote human development, improve the function of central nervous tissue and enhance immune function, and if it is deficient, it will lead to poor development, lack of appetite, etc. The common dosage forms of this drug are tablets and injection. The commonly used dosage forms of this drug are tablets and injections, of which tablets can be used for lysine deficiency-induced loss of appetite, malnutrition, etc.; injections can be used as a cerebral protective agent for chronic cerebral tissue ischemia, craniocerebral trauma, and hypoxic diseases. Contraindications to the use of tablets include those who are allergic to the product and those with severe hepatic or renal insufficiency; contraindications to the use of injections are not clear, but they should be used with caution in patients with acute ischemic cerebrovascular disease. Mild nausea, vomiting and allergic reactions are occasionally seen after use. The specific use of drugs should be carried out under the guidance of specialists, not unauthorized use of drugs.