This happened to me within 3 weeks of taking this new manufacturer & I ended up in the hospital for 5 days as it caused me to go from hypocalcemic to hypercalcemic. This also caused my potassium & magnesium levels to go to critical lows that required IV medications. I've never been diagnosed hypercalcemic in the 14 years since my TT & that switch was the only change with my medications, I've always taken the same manufacturer. It took about 6-8 weeks of taking no calcium or calcitriol for my levels to go back to my "happy place" (calcium in the 8-9 range). I'm still having some issues with my magnesium & potassium levels that are slowly getting back to the normal range.