WHY is this medicine prescribed?
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.
HOW should this medicine be used?
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.
Are there OTHER USES for this medication?
This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
What SPECIAL PRECAUTIONS should I follow?
Before taking magnesium oxide,
What should I do IF I FORGET to take a dose?
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.
What SIDE EFFECTS can this medicine cause?
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:
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 (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).
What should I do in case of OVERDOSE?
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.
What should I know about STORAGE and DISPOSAL of this medication?
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).
Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website http://goo.gl/c4Rm4p for more information.
Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach. http://www.upandaway.org
What OTHER INFORMATION should I know?
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.
Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.
This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.
The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.
AHFS® Patient Medication Information™ Copyright, 2025. The American Society of Health-System Pharmacists®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.
Selected Revisions: June 20, 2024.