It is perfectly safe to use as long as you take sensible doses. You can't overdose on magnesium, the excess is just flushed out in urine and feces.

The first sentence referencing sensible doses is almost correct. The second assuring that overdose is impossible is dangerously wrong. Massive doses of oral magnesium can lead to toxicity, and sensible doses in someone who has impaired renal function, may do so as well. Do you know your glomerular filtration rate this morning?

LOL perhaps I did use an unfortunate choice of words there...what I really meant was that you're not going to overdose on Mg by taking the normal supplemental amount. You can overdose on water if you drink enough of it (and it's not really that much). But if you're taking more than your body really needs, it will flush the excess. What I'm saying is that you shouldn't really worry about long term toxicity from taking a magnesium supplement.