Spironolactone
"Please be careful on this drug.  It is a diuretic and can cause your sodium to drop, especially if you drink a lot of water.  I became increasingly lightheaded and dizzy.  I was vomiting.  I went to the ER and my sodium was 118.  Normal is around 135-145.  This is dangerously low.  Under 115 and your brain can swell leading to seizure, herniation, and death.  If you're having symptoms please stop taking the medicine and have your labs checked."