Antacids are over-the-counter medications used to relieve heartburn, indigestion or acid reflux. They can be formulated with magnesium, aluminum, calcium or a combination of magnesium and aluminum together. Antacids should only be used for occasional symptoms. If symptoms occur consistently or frequently, see your health care provider. Although these medications are generally safe, there are side effects associated with their use.
Magnesium antacids, such as milk of magnesia, can cause nausea and vomiting, but the major side effect is diarrhea. Others also contain aluminum. Since a side effect of aluminum-containing antacids is constipation, the two tend to balance each other, reducing the occurrence of abdominal side effects. University of Puget Sound indicates that you should seek advice from a medical professional if nausea and vomiting last for longer than a day or if diarrhea lasts more than 48 hours.
Magnesium antacids relieve indigestion and heartburn by neutralizing stomach acid. Your body must have an appropriate amount of stomach acid to absorb nutrients such as calcium, vitamin B12, iron, folic acid and zinc. According to Penn State University, magnesium antacids can decrease the absorption of these nutrients. These drugs can also bind to phosphate so that the body cannot absorb it. Inability to absorb nutrients leads to various vitamin deficiencies. Low phosphate and calcium levels can cause muscle weakness and osteomalacia. Iron and B12 deficiencies can also cause anemia. Additionally, pregnancies may be compromised if the mother does not receive adequate amounts of folic acid.
Magnesium-containing antacids can alter the effectiveness of many drugs. Certain antibiotics, such as quinolone and tetracycline, may not be absorbed when taken with magnesium antacids. University of Maryland Medical Center states that you should take magnesium one hour before taking these antibiotics or wait two hours after taking antibiotics to take the antacids.
Magnesium hydroxide, found in milk of magnesia, may increase absorption of diabetes medications glyburide and glipizide. This may actually be beneficial in maintaining a reduced blood sugar. Since magnesium may block the absorption of bisphosphonates used to treat osteoporosis, magnesium-containing antacids should be taken either one hour before or two hours after oral bisphosphonates.