"Taking 60,000 international units (IU) a day ...for several months has been shown to cause toxicity. This level is many times higher than the U.S. Recommended Dietary Allowance (RDA) for most adults of 600 IU of vitamin D a day."
60,000??? For MONTHS?? Jez, Louise! the biggest tablets I've seen over counter are 5k each. So...12 a day...every day...for MONTHS?
Well, you can kill yourself with drinking too much water or taking too many aspirin, also.
I mention the 50 ng/dl so you have a target. 5000 IU/day got me to about 35 ng/dl, so I upped it to 10,000 to get 55 ng/dl. Your milage may vary -- so asking your doctor to measure Vitamin D from time to time as part of your regular lab work seems wise to me.
And I've heard various vitamins can interact with various other medications, so you should fill your doctor in on that, also -- if you have a decent doctor. And if you don't have a doctor who will do anything but put you on a ventilator and give you remdesivir, you might want to find find that out in advance!
FYI, I have a much longer list of things to fend off Covid than what I mentioned; Vitamin C (as Micro suggests) is probably wise, also! But I don't take eerything all the time. I take a LOT of things, and in higher quantities, whenever I feel I might be coming down with something or if I have been around a lot of people...or preparing to fly in a plane.
I just picked up some HCQ and more Ivm because I can get them over the counter in S. America. Sometimes the US is really too much of a nanny state. Well, in truth, MOST of the time!