Pharmacokinetics of a single large dose of cholecalciferol
Patients are frequently concerned with what they consider “high” dosages of Vitamin D. They look at their bone formulas, multivitamins and Vitamin D and think that they are going to overdose. While overdose is possible, the window of safety is very large with Vitamin D and usually requires dosages over 10,000 IU / day for several months before an issue may arise.
In this particular study they used a dosage of 100,000 IU at one time and found no notable side effects, with the authors recommending this level of dosage to be given every 2 months. Kind of makes you less worried about that whopping 400 IU in your calcium supplement your doctor recommended, huh?