Definition of Milk of Magnesia

Milk of magnesia is a medication available as an over-the-counter product that is used as a laxative in addition to treating conditions related to stomach acid such as heartburn or indigestion. The active ingredient in milk of magnesia is magnesium hydroxide. It is believed to work as a laxative by drawing water into the intestinal tract. Milk of magnesia is available in liquid and chewable forms. Extended use or overuse of this medication for constipation may result in dependence on laxatives or chronic constipation.