Hypervitaminosis A is a toxic nutrition disorder caused by over-consumption of Vitamin A supplements or foods that are very high in Vitamin A content, like animal liver. It is characterized by inflammation, dryness and discoloration of the skin, particularly at the corners of the mouth, as well as hair loss.
Hypervitiminosis A can develop because, as a fat soluble vitamin, the body will tend to store any vitamin A in excess of the body's needs rather than secreting it in the urine or stool. 80% of any surplus is generally stored in the liver, where in excess it can have a toxic effect. In extreme cases, it can cause permanent liver damage.
As a rule, the condition can be prevented by sticking close to dietary recommendations, which range from 600 micrograms a day for children to 3000 micrograms a day for adults. This is the typical amount in a balanced diet, and is also the typical amount in over-the-counter supplements. As such, toxicity from normal dietary habits is exceedingly rare and the condition almost always develops from the overuse of supplements.
In most cases, discontinuing high doses of Vitamin A will result in full recovery.