Just like anything, too many electrolytes can be unhealthy. Damage from excess electrolytes Excess sodium (hypernatremia) can cause dizziness, vomiting, and diarrhea. Excess potassium (hyperkalemia) can impact your kidney function and cause heart arrhythmia, nausea, and an irregular heartbeat. Excess calcium (hypercalcemia) can lead to fatigue, lethargy, seizures, and bone and joint pain. Excess magnesium can cause muscle weakness, nausea, dizziness, confusion, and heart arrhythmia, and at worst - muscular and neurological damage.