Magnesium sulfate (epsom salt) may be used at say 1/4- more tsp in water to restore magnesium levels. Take it in smaller amounts than what causes purging. Epsom Salt may also be taken in through the skin in a foot soak or bath. Finally Epsom Salt may be deposited rectally for optimum absorption. In addition increase magnesium levels in food most of us have magnesium deficiency read about it here before deciding course of action.