So how does one determine what dose a child should have and when it should be given? Does the doctor regulate the dosing schedule, or do parents use trial and error to see what works best? Is it used primarily to control weight and growth - neither of which my daughter has a problem with? She does have a problem with headaches and intermittent feelings of just not feeling good. When she doesn’t "feel right" it doesn’t usually last very long, but it’s enough of a problem that she’s been missing quite a bit of school. Her renin levels are out of whack right now, something that’s never happened before, and I’m sure that’s part of it. But she’s also had these episodes before (though not always as often) even when her levels were good. I’m just trying to look into whatever options there might be that could make a difference. I’d be interested in whatever references or links you had so that I could learn a little more. Thanks for your explanation and help.