I experienced (almost immediately) adverse effects that included 5 of the about 7 possible AEs listed on the
package insert, including heart palpitations, urinary frequency, etc, just look on the insert. After a few days I'd feel great then my D levels started plummeting (most probably) and then I'd take another 50,000 IUs and have AEs. Of course I'm older in my sixties so my age might have had something to due with my inability to process and perhaps convert D2 to D3.