The role and efficacy of vitamin A for the treatment of vitamin A deficiency, vitamin A hypervitaminosis patients are prohibited, adverse reactions include chronic poisoning, acute poisoning. 1.Role and efficacy: for vitamin A deficiency, such as corneal softening, dry eye, skin roughness keratosis, night blindness. 2. Contraindications: Prohibited in patients with vitamin A hypervitaminosis. It is forbidden for those who are allergic to any of the ingredients. 3.Adverse reactions: (1) Chronic poisoning: overdose, when the use of more than 6 months, chronic poisoning can occur, manifested as increased intracranial pressure, dryness, desquamation, itchy skin, diarrhea, vomiting, lack of appetite. (2) Acute poisoning: it may manifest as increased intracranial pressure, drowsiness, diplopia, abnormal agitation and other symptoms. Patients with vitamin A deficiency should not take medication on their own, but should go to the hospital in time and receive standardized treatment under the guidance of a doctor.