Vitamin A should not be taken daily or for a long period of time. Vitamin A as a fat-soluble vitamin, the main effect is to prevent and treat vitamin A deficiency caused by night blindness, skin roughness, corneal softening, and dry eye disease, etc., in the symptom has been improved or cured, the drug needs to be discontinued in time. Vitamin A is not associated with any significant adverse effects when taken in normal doses, but when used in large doses over a long period of time, acute or chronic toxicity may occur. Acute poisoning is mainly manifested as dizziness, headache, itching and diarrhea, etc. Chronic poisoning is mainly characterized by bone and joint pain, skin itching, swelling and general discomfort. Vitamin A and a variety of drugs may interact with each other, so in the use of the process should try to avoid combining, such as anticoagulants, diuretics, digitalis drugs and so on. It is contraindicated in cases of hypervitaminosis A. The use of this drug must follow the doctor’s instructions, do not blindly use their own medicine, so as not to cause adverse consequences.