Hypervitaminosis is a condition of abnormally high storage levels of vitamins, which can lead to various symptoms as over excitement, irritability, or even toxicity.

Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but natural food in modest levels rarely deliver extreme or dangerous levels of fat-soluble vitamins.

For those who are entirely healthy and do not experience long periods of avitaminosis, 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.

[2] Conditions include: Prevention in healthy individuals not having any periods of avitaminosis or vitamin (vegetables) lack for 2 years at least is by not taking more than the expected normal or recommended amount of vitamin supplements.

[3] 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).