Dehydration can happen faster than many people realize. Whether it’s caused by hot summer weather, intense exercise, illness, vomiting, diarrhea, or simply not drinking enough fluids, dehydration can leave you feeling tired, dizzy, weak, and unable to function at your best. When dehydration develops, many people immediately start drinking large amounts of water. While replacing lost fluids is important, rehydrating effectively involves more than simply drinking as much water as possible. The safest and ...