In most cases, children can take vitamin AD drops until they are about 2 years old because they are prone to vitamin D deficiency rickets within 2 years of age. When vitamin D deficiency rickets occurs, it can cause chicken chest, ribbed beads, X-shaped legs, O-shaped legs, sleep disturbance, night crying and so on, which have a great impact on the growth and development of children. Vitamin AD drops can prevent and reduce vitamin D deficiency rickets in children. In addition, children also tend to have vitamin A deficiency, which can manifest itself as a loss of dark vision at night and frequent recurrent respiratory infections. The immunity of children increases greatly until they are 2 weeks old and their dietary intake of vitamin A as well as D slowly increases, at which time it can be gradually discontinued.