<P> Hyperkalemia is the most serious adverse reaction to potassium . Hyperkalemia occurs when potassium builds up faster than the kidneys can remove it . It is most common in individuals with renal failure . Symptoms of hyperkalemia may include tingling of the hands and feet, muscular weakness, and temporary paralysis . The most serious complication of hyperkalemia is the development of an abnormal heart rhythm (arrhythmia), which can lead to cardiac arrest . </P> <P> Although hyperkalemia is rare in healthy individuals, oral doses greater than 18 grams taken at one time in individuals not accustomed to high intakes can lead to hyperkalemia . Supplements sold in the U.S. are supposed to contain no more than 99 mg of potassium per serving . </P>

Where is the majority of potassium located in the body