Overview: Magnesium antacids are taken to help relieve indigestion, heartburn, or a sour stomach. You may notice that your poop may be loose, watery, or more frequent when taking a magnesium antacid.

Lindsay Cook, PharmD, is a consultant pharmacist working with long-term care facilities. High doses of magnesium glycinate may cause diarrhea, gas, or stomach pain. Very high or long-term use can lead ...