After four weeks, hot flashes had declined from an average frequency of 52 per week to 28 per week, or 41 percent lower. Also, hot flash severity declined by at least 25 percent in three out of four of the women.
Side effects were few and minor, and many of the women continued to take magnesium for hot flashes after the study ended. Because of these promising findings and the low cost of magnesium tablets, researchers are planning a placebo-controlled study.