Two year olds can be supplemented with vitamin AD combinations, and in general no additional calcium supplements are needed if there are no clinical signs. Foods high in calcium, such as milk, can be consumed daily. Vitamin AD is a combination of vitamin D and vitamin A. It can be used to prevent vitamin D deficiency rickets and night blindness in children. Generally there are relatively few adverse effects and its being a capsule drop is good for compliance with medication in 2 year olds. However, there may be gastrointestinal adverse reactions manifested as vomiting, constipation, diarrhea, nausea, etc., so the dosage needs to be taken under medical supervision. If the baby has obvious symptoms of low calcium, it is recommended to consult a doctor in a timely manner, improve the blood calcium and other related tests, such as low blood calcium, if necessary, can be prescribed by the doctor to be treated with calcium gluconate.