Amino acid injections are mostly compound preparations, formulated from a variety of amino acids. According to the different kinds of amino acids, it can be divided into 9AA, 14AA, 5AA, 18AA, often containing proline, serine, alanine, leucine, menthionine, glutamic acid, etc. It is used for the treatment of patients with insufficient intake of protein, impaired absorption and other amino acids that can not meet the metabolism of the body, and also used to improve the nutritional status of postoperative patients. It is also used to improve the nutritional status of postoperative patients. It is forbidden for patients with severe hepatic and renal insufficiency, uremia and patients with metabolic disorders of amino acids. There are many kinds of amino acid injection in China. The price also varies greatly, and the common price is 5-30 yuan for 1 bottle.