The electrolytes you need include primarily potassium, sodium, calcium, magnesium, chloride...but there are others as well. Most sports drinks contain electrolytes because you lose them when you sweat...or have diarrhea or vomiting, but they also contain a lot of sugar. That's why I go with EmergenC.
The side effects listed are brought about by overuse of magnesium citrate or if you already had an electrolyte problem, were dehydrated or had constipation due to a blockage. You would have the same effects with overuse of magnesium sulfate or if any of these conditions existed.