Hypervitaminosis D symptoms appear several months after excessive doses of vitamin D are administered.
Prolonged administration can cause severe damage to the bones, soft tissues, and kidneys.
An excess of vitamin D causes abnormally high blood concentrations of calcium. Furthermore, excess vitamin D promotes the return of calcium from the bones to the blood stream. This excess blood calcium tends to deposit in the soft tissues of the body. Stone formation is especially likely in the kidneys, where the body attempts to excrete the calcium. Hardening of the blood vessels may also occur, and present life-threatening problems over time when the vessels of the heart and lungs are involved.