For about 2 years I have been taking 6,000 I.U./day of Vitamin D3 during daylight savings while going to 10,000 I.U./ day during standard time. At times when everyone is getting the flu I have taken as much as 24,000 I.U. /day for a maximum of 4 days.
I have read that toxicity with Vitamin D does not begin until until someone is getting around 40,000 + I.U. /day for a number of months. I also understand that any toxicity is reversible with cessation of Vitamin D intake.
I have not personally experienced any toxicity to date.