How long an adult should supplement with vitamin A tablets needs to be based on the level of vitamin A deficiency in the body. Any vitamin medication is not recommended to be taken blindly for a long period of time, as too long a period of time can cause adverse reactions and effects. Vitamin A can promote the body’s growth, bone development, improve vision, as well as maintain epithelial tissue, mucosal epithelial secretion and other physiological functions. In case of deficiency, it will show symptoms such as growth retardation, reduced adaptability and night blindness. Vitamin A tablets are mainly used for the prevention and treatment of vitamin A deficiency. Such as dry eye, night blindness, skin roughness keratosis, corneal softening and so on. Long-term large doses of vitamin A tablets can easily lead to the emergence of chronic poisoning symptoms, such as lack of appetite, nausea, vomiting, diarrhea, dry skin, flaking and other symptoms, acute poisoning can be seen with abnormal emotional agitation, diplopia, increased intracranial pressure, drowsiness and other symptoms. It is recommended that when using the drug, it should be taken under the guidance of a doctor to avoid causing adverse reactions and effects.