Generic Name: magnesium oxide (mag NEE see um OCK side)
Brand Name: MagGel, Phillips' Cramp-free, Uro-Mag, Mag-200, Mag-Ox 400
What is magnesium oxide?
Magnesium is a naturally occurring mineral. Magnesium is important for many systems in the body especially the muscles and nerves.
Magnesium oxide is used as a supplement to maintain adequate magnesium in the body.
Magnesium oxide is also used as an antacid to treat indigestion, or as a laxative to relieve occasional constipation.
Magnesium oxide may also be used for purposes not listed in this medication guide.
What is the most important information I should know about magnesium oxide?
Before you take magnesium oxide, tell your doctor about all your medical conditions or allergies, and all the medicines you are using. Also make sure your doctor knows if you are pregnant or breast-feeding. In some cases, you may not be able to take magnesium oxide, or you may need a dose adjustment or special precautions.
What should I discuss with my healthcare provider before taking magnesium oxide?
You should not use magnesium oxide if you are allergic to it.
Ask a doctor or pharmacist if it is safe for you to use this medicine if you have other medical conditions, especially:
a blockage in your intestines;
low levels of calcium in your blood; or
a sudden change in bowel habits for 2 weeks or longer.
It is not known whether magnesium oxide will harm an unborn baby. Ask a doctor before using this medicine if you are pregnant.
It is not known whether magnesium oxide passes into breast milk or if it could affect a nursing baby. Ask a doctor before using this medicine if you are breast-feeding.
Do not give this medicine to a child without medical advice.
Magnesium oxide should not be given to a child younger than 6 years old.
How should I take magnesium oxide?
Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.
Take this medicine with a full glass of water.
When using this medicine as a laxative, it may be best to take your dose at bedtime.
Magnesium oxide may be taken with food if it upsets your stomach.
Call your doctor if your symptoms do not improve after 7 days of treatment, or if symptoms get worse.
Store at room temperature away from moisture and heat.
What happens if I miss a dose?
Since magnesium oxide is sometimes used when needed, you may not be on a dosing schedule. If you are on a schedule, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include nausea, vomiting, weakness, breathing problems, slow reflexes, weak pulse, extreme drowsiness, and feeling dizzy or light-headed.
What should I avoid while taking magnesium oxide?
Magnesium oxide can make it harder for your body to absorb other medicines you take by mouth. Avoid taking other medicines within 2 hours before or 2 hours after you take magnesium oxide. You may need to wait 4 hours to take your other medicines after taking magnesium oxide. Ask your doctor how to best schedule your medications.
Magnesium oxide side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using magnesium oxide and call your doctor at once if you have:
coughing up blood or vomit that looks like coffee grounds;
bloody or tarry stools; or
no bowel movement after using magnesium oxide as a laxative.
Common side effects may include:
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Magnesium oxide dosing information
Usual Adult Dose for Dyspepsia:
400 mg tablets: 1 tablet orally twice a day
Maximum dose: 2 tablets per 24 hour period
Duration of therapy: Up to 2 weeks
-May have a laxative effect.
Uses: Acid indigestion, upset stomach
Usual Adult Dose for Constipation:
Caplets (500 mg): 2 to 4 caplets orally daily with a full 8 ounce glass of liquid.
Caplets may be taken all at bedtime or separately throughout the day.
Usual Adult Dose for Vitamin/Mineral Supplementation during Pregnancy/Lactation:
Recommended DIETARY intake:
Women 19 to 30 years: 508 mg magnesium oxide (MgOx) (310 mg elemental magnesium) orally daily
Women 31 years and older: 525 mg MgOx (320 mg elemental) orally daily
Men 19 to 30 years: 656 mg MgOx (400 mg elemental) orally daily
Men 31 years and older: 689 mg MgOx (420 mg elemental) orally daily
Maximum SUPPLEMENT dose: 574 mg MgOx (350 mg elemental)
-There is no upper level of intake for magnesium from food.
Usual Pediatric Dose for Constipation:
500 mg caplets:
12 years and older: 2 to 4 caplets orally daily, as a single dose or divided dose
Maximum dose: 4 caplets per day
Duration of therapy: 7 days or less
-Bedtime is the preferred administration time for a single dose.
-Take with a full glass of water.
Usual Pediatric Dose for Vitamin/Mineral Supplementation during Pregnancy/Lactation:
Recommended DIETARY intakes:
14 to 18 years:
Males: 672 mg magnesium oxide (MgOx) (410 mg elemental magnesium) per day
Females: 590 mg MgOx (360 mg elemental) per day
Maximum SUPPLEMENT dose (both sexes): 574 mg MgOx (350 mg elemental) per day
9 to 13 years: 394 mg MgOx (240 mg elemental) per day
Maximum SUPPLEMENT dose: 574 mg MgOx (350 mg elemental) per day
4 to 8 years: 213 mg MgOx (130 mg elemental) per day
Maximum SUPPLEMENT dose: 180 mg MgOx (110 mg elemental) per day
1 to 3 years: 131 mg MgOx (80 mg elemental) per day
Maximum SUPPLEMENT dose: 107 mg MgOx (65 mg elemental) per day
7 to 12 months: 123 mg MgOx (75 mg elemental) per day
Birth to 6 months: 49 mg MgOx (30 mg elemental) per day
-There is no upper level of intake for magnesium from food.
What other drugs will affect magnesium oxide?
Ask a doctor or pharmacist if it is safe for you to take magnesium oxide if you are also using any of the following drugs:
a diuretic or "water pill";
a blood thinner--warfarin, Coumadin, Jantoven; or
medicine to treat osteoporosis or Paget's disease--alendronate, ibandronate, risedronate, Fosamax, Boniva, Actonel, and others.
This list is not complete. Other drugs may interact with magnesium oxide, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
More about magnesium oxide
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Support Group
- Pricing & Coupons
- En Español
- 13 Reviews – Add your own review/rating
- Drug class: minerals and electrolytes
Related treatment guides
Where can I get more information?
- Your pharmacist can provide more information about magnesium oxide.
- Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
- Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.
Copyright 1996-2012 Cerner Multum, Inc. Version: 4.01.
Last reviewed: April 28, 2017
Date modified: July 24, 2017