Hypervitaminosis

Hypervitaminosis is a condition of abnormally high storage levels of vitamins, which can lead to toxic symptoms. Specific medical names of the different conditions are derived from the vitamin involved: an excess of vitamin A, for example, is called hypervitaminosis A. Hypervitaminoses are primarily caused by fat-soluble vitamins (D and A), as these are stored by the body for longer than the water-soluble vitamins.
Generally, toxic levels of vitamins stem from high supplement intake and not from natural food. Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but natural food rarely deliver dangerous levels of fat-soluble vitamins. The Dietary Reference Intake recommendations from the United States Department of Agriculture define a "tolerable upper intake level" for most vitamins.
Vitamin overdose can be avoided by not taking more than the normal or recommended amount of multi-vitamin supplement shown on the bottle and not ingesting multiple vitamin-containing supplements concurrently.
Signs and symptoms.
Organs compromises:
Causes.
With few exceptions, like some vitamins from B-complex, hypervitaminosis usually occurs with the fat-soluble vitamins A and D, which are stored, respectively, in the liver and fatty tissues of the body. These vitamins build up and remain for a longer time in the body than water-soluble vitamins. Conditions include:
Prevention.
Prevention is by not taking more than the normal or recommended amount of vitamin supplements.
Epidemiology.
In the United States, overdose exposure to all formulations of "vitamins" (which includes multi-vitamin/mineral products) was reported by 62,562 individuals in 2004 with nearly 80% of these exposures in children under the age of 6, leading to 53 "major" life-threatening outcomes and 3 deaths (2 from vitamins D and E; 1 from a multivitamin with iron). This may be compared to the 19,250 people who died of unintentional poisoning of all kinds in the U.S. in the same year (2004). In 2016, overdose exposure to all formulations of vitamins and multi-vitamin/mineral formulations was reported by 63,931 individuals to the American Association of Poison Control Centers with 72% of these exposures in children under the age of five. No deaths were reported.