Water–mineral balance functions like the body’s electrical system. When fluid loss rises (sweating, diarrhea, fever, low intake), electrolyte balance—sodium, potassium, magnesium—can shift. Mild depletion may cause headaches, dry mouth, reduced performance and focus, and constipation. Moderate imbalance adds cramps, palpitations, low blood pressure, dizziness, and reduced urine output. Severe cases can involve confusion, fainting, or dangerous arrhythmias. People exercising hard, working in heat, experiencing vomiting/diarrhea, or older adults may need electrolyte-containing fluids rather than “water only.” In chronic kidney or heart disease, however, electrolyte or salt intake should not be increased without medical guidance. Best prevention is steady hydration, mineral-dense foods, and tailored electrolyte support during high-loss periods.\n\nSource note: Principles consistent with NIH ODS mineral fact sheets and electrolyte physiology.