Magnesium + Potassium 400 is a dietary supplement used by adults and children over 12 years of age. It contains magnesium, which contributes to the maintenance of normal muscle function and helps reduce fatigue and weakness. Potassium contributes to the normal functioning of the nervous system and helps to maintain normal blood pressure. Zinc supports the proper functioning of the immune system. Iron and vitamins B6 and B12 contribute to the normal formation of red blood cells.