Vitamin AD and Vitamin D3, there is no optimal time to take these two medications, so take them as prescribed by your doctor. Vitamin A and vitamin D are essential substances for human growth and development, which are beneficial to the growth and development of infant eyesight, reproductive organs, bones and teeth. Vitamin D3 is commonly used in the prevention and treatment of vitamin D deficiency, such as rickets, osteomalacia, hand and foot cramps, etc. The above medications are chosen in infancy according to individual development. However, there are no specific rules on when it is best to take vitamin AD or vitamin D3 in a day. The details should be taken according to the doctor’s prescription. It is recommended that after taking the medication, appropriate sun exposure outdoors is conducive to the absorption and utilization of the medication. In addition, vitamin AD and vitamin D3 are not recommended to be taken together for a long period of time, both drugs can maintain and increase the blood calcium concentration, there is a risk of hypercalcemia, need to be staggered and alternated. It is recommended to take medication under the guidance of a doctor, not to take medication privately.