Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative for short-term, rapid emptying of the bowel (before surgery, for example). It should not be used repeatedly. Magnesium oxide also is used as a dietary supplement when the amount of magnesium in the diet is not enough. Magnesium oxide is available without a prescription.
Magnesium oxide comes as a tablet and capsule to take by mouth. It usually is taken one to four times daily depending on which brand is used and what condition you have. Follow the directions on the package or on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take magnesium oxide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Take any other medicine and magnesium oxide at least 2 hours apart.
If you are using magnesium oxide as a laxative, take it with a full glass (8 ounces [240 milliliters]) of cold water or fruit juice. Do not take a dose late in the day on an empty stomach.
Do not take magnesium oxide as an antacid for longer than 2 weeks unless your doctor tells you to. Do not take magnesium oxide as a laxative for more than 1 week unless your doctor tells you to.
This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
Before taking magnesium oxide,
- tell your doctor and pharmacist if you are allergic to magnesium oxide, other antacids or laxatives, or any other drugs.
- tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially other antacids or laxatives, anticoagulants ('blood thinners') such as warfarin (Coumadin), aspirin, diuretics ('water pills'), medicine for ulcers (cimetidine [Tagamet], ranitidine [Zantac]), and vitamins.
- tell your doctor if you have or have ever had heart, kidney, liver, or intestinal disease or high blood pressure.
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking magnesium oxide, call your doctor immediately.
- tell your doctor if you are on a low-salt, low-sugar, or other special diet.
If you are taking magnesium oxide on a regular schedule, take the missed dose as soon you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Magnesium oxide may cause side effects. To avoid unpleasant taste, take the tablet with citrus fruit juice or carbonated citrus drink. Tell your doctor if either of these symptoms are severe or do not go away: If you experience any of the following symptoms, call your doctor immediately:
- rash or hives
- dizziness or lightheadedness
- mood or mental changes
- unusual tiredness
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at Web Site] or by phone [1-800-332-1088].
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
If this medicine has been prescribed for you, keep all appointments with your doctor so that your response to magnesium can be checked.
Do not let anyone else take your medicine.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
AHFS® Consumer Medication Information. © Copyright, The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.
Last Reviewed: February 1, 2009.