What Is Magnesium Oxide?

Benefits, Side Effects, Dosage, and Interactions

Much like other types of magnesium, magnesium oxide has many health benefits. When used regularly, magnesium oxide can help boost low magnesium levels, relieve constipation, manage depression, treat migraines, and more. 

Magnesium oxide is a type of magnesium mineral supplement that is mostly made of magnesium—it actually contains more magnesium than other magnesium supplements. Magnesium oxide is acquired by burning magnesium with pure oxygen, but this method is quite costly. The cheaper method is to expose oxygen to magnesium salts using underground deposits, seawater, or salt beds. With this method, the source of the magnesium salt determines the quality of the magnesium oxide that is produced.

Benefits of magnesium oxide

Verywell​ / Brianna Gilmartin

What Is Magnesium Oxide Used For?

Magnesium oxide offers some impressive health benefits and can help to relieve the symptoms of a variety of conditions.

Regulates Magnesium Levels

Magnesium deficiency has a number of contributing factors including diet, food allergies, alcoholism, and poor kidney health. Symptoms of magnesium deficiency may include:

  • Leg cramps
  • Cardiac issues: arrythmias, palpitations, blood pressure changes, murmurs
  • Muscle and bone pain
  • Anxiety and depressed moods
  • High blood pressure
  • Insomnia
  • Fatigue

Supplementation of magnesium oxide can maintain healthy levels of magnesium throughout the body. In fact, supplementation eliminates many of the symptoms associated with deficiency.

Manages Gastrointestinal Problems

When magnesium oxide is mixed with water, it is called magnesium hydroxide—this mixture can help with naturalizing stomach acids. One study of 276 people found that a combination of simethicone (an agent used to decrease gas), activated charcoal, and magnesium oxide was more effective than a placebo for managing indigestion. Many antacids use magnesium hydrogen-based substances, but few studies have looked at the effectiveness of magnesium oxide alone.

Relieves Depression 

Magnesium oxide may help manage depressive symptoms and behaviors, as it may have positive mental health and stress reduction effects. Several studies have confirmed an association between magnesium intake and depression.

Reduces Blood Pressure and Risk of Stroke

Research from the American Journal of Clinical Nutrition finds that diets high in magnesium can reduce the risk of stroke, especially ischemic strokes. This type of stroke occurs when the artery to the brain is blocked.  The cause of most ischemic strokes is high blood pressure, and research finds that magnesium supplementation can help to lower blood pressure.

Reduces Migraines

Magnesium oxide supplementation may reduce the number and intensity of migraines. Research shows the majority of migraine sufferers are magnesium deficient. The American Migraine Foundation finds magnesium to be an ideal treatment for migraine relief and prevention.

Lowers Colorectal Cancer Risk

Some research indicates magnesium oxide supplements may reduce the risk of colorectal cancer. Research reported in the American Journal of Clinical Nutrition finds that high doses of magnesium are linked to a lowered risk of colorectal tumors. The report suggests that for every 100-milligram increase in magnesium, the risk of developing a tumor is reduced by 12%.

Possible Side Effects

Upset stomach and diarrhea are the most common side effects of magnesium oxide. Taking magnesium oxide with food can reduce stomach troubles. If side effects are persistent or if they worsen, it is best to talk to your healthcare provider. Most people using magnesium oxide supplements do not have serious side effects.

Serious allergic reactions to magnesium oxide are rare. However, anyone who has symptoms of rash, itching, swelling, severe dizziness and/or trouble breathing should seek immediate medical attention. 

People with kidney problems should talk to their healthcare providers before starting magnesium oxide supplements. In addition, pregnant and breastfeeding mothers should avoid magnesium oxide as risks are unknown.

It is crucial to consult with a healthcare provider before starting or continuing supplements.

Dosage and Preparation

The recommended daily allowance (RDA) of magnesium for young adults is 400 mg per day for men and 310 mg per day for women. In adults over 30 years old, the RDA is 420 mg per day for men and 320 per day for women.

Magnesium oxide supplements should be taken by mouth with meals to reduce stomach upset. Supplements should not be crushed or chewed because doing so will increase the risk of side effects. If taken in liquid form, shake and measure the proper dose according to instructions on the supplement's label.

If you take magnesium supplements, they should be taken regularly and at the same time daily in order to get the most benefit. Dosage should not be increased without a healthcare provider's approval. If you are taking a magnesium supplement, any missed doses should be taken as soon as you remember—if it is already time for the next dose, then the missed dose should be skipped. Doses should not be doubled up.

Though magnesium oxide provides a host of health benefits, too much magnesium in the blood can cause serious side effects.

Anyone who thinks they have low magnesium levels should talk to their healthcare provider. The most common symptoms of deficiency are muscle cramping, fatigue, depression, and irritability.

What to Look For

Magnesium oxide supplements are available over-the-counter (OTC) without a prescription. Magnesium oxide is sold under several brand names including Mag-Ox 400, Uro-Mag, and Magox. Your healthcare provider or pharmacist can advise you on which brand might be a good fit for your unique situation and overall health.

Before picking up a magnesium supplement, it is a good idea to have your magnesium levels checked by a healthcare provider. There is no way to know if any symptoms you might be experiencing are related to a magnesium deficiency, another deficiency, or an illness. You should always disclose all health conditions and medications to avoid interactions and adverse reactions.

A Word From Verywell

Getting enough magnesium is important for good health. Without it, the body cannot function. Magnesium can be ingested by eating foods rich with magnesium such as salmon, quinoa, and black beans. Although your daily dose of magnesium is crucial, consuming magnesium in excessive quantities can be detrimental to your health. Be sure to consult with a healthcare provider if you have symptoms of magnesium deficiencies or if you are considering taking a magnesium supplement.

Frequently Asked Questions

  • What is the difference between magnesium and magnesium oxide?

    Magnesium oxide is a type of magnesium that also contains oxygen. Other forms of magnesium supplements include: 

    • Magnesium chloride
    • Magnesium citrate
    • magnesium glycinate
    • Magnesium lactate
    • Magnesium malate
    • Magnesium orotate
    • Magnesium sulfate
    • Magnesium L-threonate
  • What is magnesium oxide used for?

    Magnesium oxide is primarily used to treat magnesium deficiency. Signs of magnesium deficiency include:

    • Anxiety
    • Cardiac issues including arrhythmias, heart palpitations, and heart murmurs
    • Depression
    • Fatigue
    • Hypertension
    • Insomnia
    • Leg cramps
    • Muscle and bone pain

    Other potential uses for magnesium oxide include 

    • Heartburn and indigestion
    • Lower risk of colon cancer
    • Migraines
    • Reduce the risk of stroke
  • Is it safe to take magnesium oxide daily?

    Typically, yes, it is safe to take magnesium oxide daily. However, you should check with your doctor before taking any supplement on a long-term basis.

  • What is the best source of magnesium?

    The best way to get magnesium is through diet and eating a variety of magnesium-rich foods, such as salmon and mackerel, quinoa, black beans, pumpkin seeds, and dark chocolate. Supplements are an option for maintaining magnesium levels in people whose magnesium levels remain low despite diet changes.

  • How do I determine if I should take a magnesium oxide supplement?

    A healthcare provider is in the best position to determine if magnesium oxide supplements are needed for maintaining and/or increasing magnesium. Anyone who thinks their magnesium is low should talk to their healthcare provider before starting a magnesium supplement. 

Was this page helpful?
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health Office of Dietary Supplements. Magnesium Fact Sheet for Health Professionals.

  2. Coffin B, Bortolloti C, Bourgeois O, Denicourt L. Efficacy of a simethicone, activated charcoal and magnesium oxide combination (Carbosymag®) in functional dyspepsia: Results of a general practice-based randomized trial. Clinics and Research in Hepatology and Gastroenterology. 2011;35(6-7):494-499. doi:10.1016/j.clinre.2011.02.009

  3. Tarleton EK, Littenberg B. Magnesium intake and depression in adults. J Am Board Fam Med. 2015 Mar-Apr; 28(2):249-56. doi:10.3122/jabfm.2015.02.140176

  4. Larsson SC, Orsini N, Wolk A. Dietary magnesium intake and risk of stroke: a meta-analysis of prospective studies. Am J Clin Nutr. 2012 Feb; 95(2):362-6. doi:10.3945/ajcn.111.022376

  5. Mauskop A, Varughese J. Why all migraine patients should be treated with magnesium. J Neural Transm (Vienna). 2012 May;119(5):575-9. doi:10.1007/s00702-012-0790-2

  6. American Migraine Foundation. Magnesium.

  7. Wark PA, Lau R, Norat, et al. Magnesium intake and colorectal tumor risk: a case-control study and meta-analysis. Am J Clin Nutr 2012; 96:622–31. doi:10.3945/ajcn.111.030924

  8. Medline Plus. Magnesium Oxide.

Additional Reading