The clinical manifestations of hyperkalemia are not specific. Early symptoms often include numbness in the limbs, sensory abnormalities, extreme fatigue, and muscle pain. In severe cases, there can be difficulties in swallowing, speaking, and breathing, paralysis of the limbs, and tendon reflexes may disappear. The central nervous system may show signs of restlessness, fainting, and confusion. Some may experience a slow heart rate, ventricular fibrillation, and in the most severe cases, it can lead to cardiac arrest. Other symptoms may include nausea, vomiting, diarrhea, and other gastrointestinal symptoms.