I have never taken a large dose I do have low vit D on blood tests but I cannot take it. I tried even the low dose of 400mg a day and can't take it more than a couple of days without bad effects.
I don't know how other people can stand it or why I can't but I do know I will not take it again.
I took one dose of 1000 mg to start with that caused a severe reaction of pounding heart blinding circles of light around both my eyes and a horrid stay in bed head ache. If the headache had not been so bad I may have taken my pounding heart to emerg.
I went to bed and reported this to my doc who sent me to an endo doc who tested me by blood and urine tests ordered to take 400mg for a month and retest. Except I could not stand the 400mg for more than a couple of days in a row I was agitated mean could not sit still had bad insomnia. I could not reach the doc to tell her as she was on vacation for the month. So I did the best I could with what was expected of me. I took the 400mg of vit D3 as many days in a row as I could stand and then quit a couple of days to get some sleep and bring my nerves back inline then started again I continued like this till the next apt forcing myself to endure symptoms the last 7 days in a row and taking the Vit D so she could get a good test result. I was hoping she would have some answers for me at the end of this mess that would make it worth the bother.

This is the result of my testing Vit D levels before any supplements was the highest recorded during all this.
After 1000mg reaction and further test Vit D was at the second highest tested during this period.
After taking Vit D3 for most of the month test of Vit D was the lowest it had ever been all these tests were deficient.

I am not sure what is causing this the doc who did these tests said the dose of Vit D3 must not have been high enough to change my D status??? The doctor said Dit D3 cannot cause the symptoms I had. End of conversation.

That is sad as I know it did causes these symptoms. I stopped it 3-4 times and the symptoms stopped or lessened and came back when I took it again. I have not idea what is going on with me and no further follow up has been suggested. I have been told to take Vit D3 every day but I don't take it and will not take it until somebody figures out what is going on so far they obviously don't know in my case anyway.

Personally I don't think they know the entire story yet and would not suggest anyone take vit D if it causes them negative symptoms as I think our bodies know something. I would appear at first glance my body does not like Vit D3 and the more I take the harder my body has to work to get rid of it. I have had a CBC and it was fine.

I am looking for ideas as to what the cause may be and where to go from here.