Lysine for children is usually taken in a course of two weeks to one month, and can be dissolved in water, milk or porridge. Lysine is one of the 20 essential amino acids, but the body cannot synthesize it by itself, so it must be obtained from food. Adequate lysine supplementation can improve protein absorption and utilization, and promote growth and development. Its main effects include: 1) improving intelligence and bone development; 2) increasing appetite and improving malnutrition; 3) helping to produce antibodies and improving immunity. However, excessive intake of lysine may increase the burden on the liver and kidneys and cause damage to brain cells due to elevated blood ammonia, and may also cause loss of appetite and stagnation in children. Therefore, children should take lysine under the guidance of a doctor, usually for a period of two weeks to one month. If adverse reactions occur during the course of lysine administration, the child should be seen by a pediatrician as soon as possible. Parents need to pay attention to their children’s nutritional intake, including meat, poultry, eggs, milk, shrimp and beans, which are rich in lysine.