Magnesium Oxide: Benefits, Dosage, Interactions, and Side Effects

Magnesium oxide is a form of magnesium that is used as a nutritional supplement. It is thought to be beneficial in treating a variety of conditions including constipation, heartburn, hypertension (high blood pressure), type 2 diabetes, and migraines.

Magnesium is also essential to proper muscle function and may help relieve tight, sore, or cramped muscles. There are even studies that suggest magnesium oxidw may help relieve anxiety.

Available without a prescription, magnesium oxide is safe to use, although it may cause stomach aches and diarrhea in some. The recommended daily intake of magnesium from all sources is between 310 milligrams (mg) and 400mg for younger adults and between 320mg and 420mg for older adults.

This article discusses the benefits and uses of magnesium oxide, including the possible side effects, risks, interactions, and how it differs from other forms of magnesium (such as magnesium citrate).

Uses of Magnesium Oxide

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist, pharmacist or doctor. No supplement is intended to treat, cure, or prevent a disease.

Magnesium oxide is a type of magnesium mineral supplement that consists of magnesium and oxygen ions. There are other types of magnesium supplements as well.

Magnesium oxide can help to relieve the symptoms of a variety of conditions. Some magnesium oxide benefits include:

Magnesium Deficiency

Magnesium deficiency in the general healthy population is uncommon, but low intakes (e.g., older adults) or losses due to health conditions (e.g., individuals with gastrointestinal diseases, type 2 diabetes, alcohol abuse) may lead to a magnesium deficiency. Symptoms of magnesium deficiency may include:

• Early signs include: loss of appetite, nausea, vomiting, fatigue, weakness
• When deficiency worsens: numbness, tingling, muscle cramps, seizures, abnormal heart rate

Note that you can receive magnesium through your diet and through supplements. Sources of foods that are good sources of magnesium are listed below. Before starting any supplements, please discuss with your healthcare provider.

Constipation

Magnesium can be a primary ingredient in some laxatives (e.g., Philips' Milk of Magnesium). Magnesium oxide should only be used for short-term as a laxative to help with constipation. If you would like to take magnesium oxide for your constipation, please discuss with your healthcare provider.

Depression 

Magnesium oxide may help with depression in individuals who have magnesium deficiency. A 2017 study found that daily consumption of 500 mg of magnesium oxide tablets for greater than 8 weeks led to both improvements in magnesium levels and depression symptoms. Note this study was in individuals who had a magnesium deficiency. More research is needed. Please discuss taking magnesium for your depression with your healthcare provider. You should never discontinue your current medication and replace with a supplement without talking to your healthcare provider.

Blood Pressure and Risk of Stroke

A study that looked at seven prospective studies published in the American Journal of Clinical Nutrition found 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.

Type 2 Diabetes

Diets high in magnesium are associated with a lower risk of type 2 diabetes. However, very few short-term clinical trials have been done. Note that the American Diabetes Association states there is not enough research to support use of magnesium supplements to improve blood glucose in people with type 2 diabetes. Please discuss taking magnesium oxide supplements with your healthcare provider before taking them if you have diabetes.

Migraines

Magnesium oxide supplementation may reduce the number and intensity of migraines. A 2019 randomized, controlled, double-blind, crossover study showed that taking 500 mg of magnesium oxide was as effective as other medications to help with migraines. The American Academy of Neurology and the American Headache Society concluded "that magnesium therapy is 'probably effective' for migraine prevention. Please discuss taking magnesium oxide supplements with your healthcare provider before taking them if you have migraines.

What Are the Side Effects of Magnesium Oxide?

Your healthcare provider may recommend you take magnesium oxide for different health reasons. However, consuming a supplement like magnesium oxide may have potential side effects. These side effects may be common or severe.

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. 

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

Recommended Dosage

The Recommended Dietary Allowance (RDA) for magnesium for young adults (19 to 30 years) is 400 mg (milligrams) 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.

When you should take your magnesium oxide supplements and how much should be discussed with your healthcare provider.

What Happens If I Take Too Much Magnesium Oxide?

It is possible to take too much magnesium oxide. Large doses of magnesium oxide can cause magnesium toxicity. This is more likely in people with kidney problems.

If you take too much magnesium oxide, you may experience:

• Nausea, diarrhea, stomach cramps, and/or vomiting
• Lethargy
• Muscle weakness
• Cardiac symptoms such as an irregular heartbeat or low blood pressure
• Trouble breathing

If you have any of these symptoms after taking magnesium oxide, seek medical care at once. 

Drug-Drug Interactions

Magnesium oxide may prevent the absorption of several medications - listed below are a few to consider. If you take any medications, please discuss taking any supplement with your healthcare provider first before taking.

• Biphosphates such as alendronate [Fosamax] (used to treat osteoporosis)
• Antibiotics such as tetracyclines [Declomycin] and quinolones [Cipro]
• Diuretics such as forosemide [Lasix], bumetanide [Bumex], hydrochlorothiazide [Aquazide]
• Proton pump inhibitors such as esomeprazole magnesium [Nexium] and Iansoprazole [Prevacid]

Sources of Magnesium Oxide

Magnesium is found in many plant and animal foods and beverages including green leafy vegetables (spinach), legumes, nuts, seeds, and whole grains. Normally foods that are higher in fiber are rich in magnesium.

Magnesium oxide supplements are available over-the-counter (OTC) without a prescription. Magnesium oxide is sold under several brand names, and 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 the 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.

Summary

Getting enough magnesium is important for good health. Without it, the body cannot function. Magnesium can be ingested by eating foods rich in magnesium. Although your daily dose of magnesium is crucial, consuming magnesium in excessive quantities can be detrimental to your health.

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.