As of March 2015, magnesium oxide costs between $2 and $40, depending upon the brand, bottle size and milligrams of magnesium oxide per serving, according to Amazon. Magnesium oxide is sold as a single-ingredient product and in products containing combinations of magnesium oxide and other nutritional ingredients.
Magnesium oxide is potentially effective for treating or preventing low levels of magnesium in the body, where it supports muscle and bone health, reports Everyday Health. Magnesium oxide may relieve indigestion and heartburn and may also be used as a laxative on a short-term basis. It is available for oral administration in many forms, including capsule, tablet and powder.