My cousin is home from the hospital. They say part of her problem with fainting was that her thyroid tanked, but that her biggest problem was that she was drinking too much plain water. I know that people think that all the emphasis on electrolyte replacement is just hype and marketing, and some of it is, but you do need to replace what you lose by sweating, especially when it's so hot. That's why people take salt tablets in the desert. So, now she understands. She's ordered foods rich in potassium and magnesium as well.