Magnesium supplements make me feel really sick. I was taking one for 3 days and on the third day, I started to feel really sick. And so I stopped. And then, a few days afterwards, I took another. And I started to feel sick again. And it happens if I take it after a meal as well. I had to use process of elimination to find out that it was the magnesium because I was taking 3 supplements at the time. I initially thought it was the combination of all three - but that isn't true. It is the magnesium alone that caused it. So if I didn't feel sick after taking them, I would (I still have like a whole tub of magnesium).