
Vitamin D Overload: High-Dose Supplements Pose Toxicity Risks
Vitamin D is essential, but excess intake from high-dose supplements can cause toxicity (hypercalcemia), with symptoms ranging from nausea and fatigue to kidney stones and, in rare cases, kidney failure or fatal bleeding if untreated. Toxicity is uncommon but rising due to popularity and mis-prescribing. Most people recover after stopping the supplement and receiving treatment. General guidance suggests 15–20 mcg (600–800 IU) daily for most people, with an upper limit of 4,000 IU (100 mcg) per day unless advised by a clinician. Emphasis is on obtaining vitamin D from sun exposure and fortified foods first, and consulting a healthcare professional when starting or stopping supplementation.






