Magnesium oxide

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.

Magnesium Oxide 400

Medically reviewed by Drugs.com. Last updated on Mar 18, 2023.

Uses of Magnesium Oxide 400:

• It is used to treat or prevent low magnesium levels.
• It is used to treat heartburn and upset stomach.
• It may be given to you for other reasons. Talk with the doctor.

What do I need to tell my doctor BEFORE I take Magnesium Oxide 400?

• If you have an allergy to magnesium or any other part of Magnesium Oxide 400 (magnesium oxide).
• If you are allergic to Magnesium Oxide 400 (magnesium oxide); any part of Magnesium Oxide 400 (magnesium oxide); or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.

This medicine may interact with other drugs or health problems.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Magnesium Oxide 400 (magnesium oxide) with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Magnesium Oxide 400?

• Tell all of your health care providers that you take Magnesium Oxide 400 (magnesium oxide). This includes your doctors, nurses, pharmacists, and dentists.
• Do not take Magnesium Oxide 400 (magnesium oxide) for more than 2 weeks unless told to do so by your doctor.
• Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using Magnesium Oxide 400 (magnesium oxide) while you are pregnant.
• Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

How is this medicine (Magnesium Oxide 400) best taken?

Use Magnesium Oxide 400 (magnesium oxide) as ordered by your doctor. Read all information given to you. Follow all instructions closely.

• Follow how to take Magnesium Oxide 400 (magnesium oxide) as you have been told by your doctor. Do not use more than you were told to use.
• Take Magnesium Oxide 400 (magnesium oxide) with food.
• Take with a full glass of water.

What do I do if I miss a dose?

• Take a missed dose as soon as you think about it.
• If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Severe diarrhea.

What are some other side effects of Magnesium Oxide 400?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If OVERDOSE is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Magnesium Oxide 400?

• Store at room temperature.
• Store in a dry place. Do not store in a bathroom.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Consumer Information Use and Disclaimer

• If your symptoms or health problems do not get better or if they become worse, call your doctor.
• Do not share your drugs with others and do not take anyone else’s drugs.
• Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about Magnesium Oxide 400 (magnesium oxide), please talk with your doctor, nurse, pharmacist, or other health care provider.
• If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

More about magnesium oxide

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• Compare alternatives
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• Reviews (19)
• Drug images
• Side effects
• Dosage information
• During pregnancy
• Drug class: minerals and electrolytes
• Breastfeeding
• En español

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Magnesium oxide

Generic name: magnesium oxide [ mag-NEE-see-um-OCK-side ]
Brand names: MagGel, Phillips’ Cramp-free, Uro-Mag, Mag-200, Mag-Ox 400, UroMag
Dosage forms: oral capsule (140 mg; 600 mg), oral tablet (250 mg; 400 mg; 420 mg; 500 mg; base 500 mg)
Drug class: Minerals and electrolytes

Medically reviewed by Drugs.com on Apr 18, 2023. Written by Cerner Multum.

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.

Warnings

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.

Before taking this medicine

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 magnesium oxide if you have other medical conditions, especially:

• kidney disease;
• heart disease;
• nausea, vomiting;
• 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.

Magnesium oxide may cause serious side effects. Stop using magnesium oxide and call your doctor at once if you have:

• rectal bleeding;
• 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 of magnesium oxide 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.

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:

• an antibiotic;
• a diuretic or “water pill”;
• penicillamine;
• 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

• Check interactions
• Compare alternatives
• Pricing & coupons
• Reviews (19)
• Drug images
• Side effects
• Dosage information
• During pregnancy
• Drug class: minerals and electrolytes
• Breastfeeding
• En español