Icosin refers to vitamin AD drops, which can be taken until about 2 years of age, and vitamin D preparations are recommended for intermittent supplementation until 18 years of age. Vitamin A is an essential vitamin, which has the ability to maintain normal vision, promote growth and development, maintain the normal function of epithelial tissues, and participate in body metabolism. Vitamin A can be consumed from food, such as vitamin A-rich animal foods and dark green vegetables. To avoid vitamin A deficiency, supplementation is recommended until after 2 years of age on a normal diet. Vitamin D is the most important biological regulator of calcium metabolism, so oral vitamin D can be started as early as 2 weeks after birth. Food intake of vitamin D is low and can be obtained through sun exposure, but continued oral intake is still recommended until after 18 years of age. Vitamin AD drops are a combination of vitamin A and vitamin D, which can be taken until about 2 years of age. And vitamin D preparations are recommended for supplementation until after the age of 18. Vitamin AD drops can be taken according to your condition by consulting your doctor at the hospital for the exact duration.