Health Benefits of Magnesium Oxide
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Medically reviewed by Suzanne Fisher, RD
Magnesium oxide is one of the most common types of magnesium used in dietary supplements.
Though it has lower bioavailability compared to other forms of magnesium, it may benefit health in several ways, including relieving headaches and easing constipation.
Here’s everything you need to know about magnesium oxide supplements, including potential health benefits, side effects, safety, and more.
Benefits of Magnesium Oxide
Magnesium oxide is an inorganic salt of magnesium formed with ions—charged atoms or molecules— of magnesium and oxygen.
It’s one of the most common forms of magnesium used in dietary supplements and can be found in multi-nutrient supplements such as multivitamin and multimineral supplements, as well as in magnesium-only supplements.
While magnesium oxide has a relatively low absorption rate compared to other forms of magnesium, such as magnesium citrate, it has been shown to offer several health benefits, such as easing headache and constipation symptoms.
May Help Treat Headaches
Multiple studies have linked magnesium deficiency with headaches, and supplemental magnesium may help improve symptoms related to several headache types, such as migraines. Magnesium may help ease headaches by preventing excessive activation of excitatory neurotransmitters, inhibiting pro-inflammatory pathways in the brain, increasing blood vessel dilation, and improving cerebral blood flow, all of which may help reduce headache symptoms.
A 2021 study that included 63 people with migraine headaches found that treatment with 500 milligrams (mg) of magnesium oxide per day for eight weeks was similarly effective for reducing the average number of migraine attacks per month as the migraine medication valproate sodium.
A benefit of using magnesium oxide to improve headache symptoms is that magnesium oxide is generally safe and associated with fewer side effects than headache medications. It’s also safe to use during pregnancy.
A 2023 study that included 203 pregnant people experiencing migraines found that treatment with magnesium oxide alone and treatment with a combination of magnesium oxide and the B vitamin riboflavin were both effective for decreasing migraine frequency, severity, and duration. Of the 154 patients who reported migraine-associated symptoms, 77% reported improvements after the magnesium treatment.
Could Help Treat Constipation
Magnesium oxide is considered an osmotic laxative. Osmotic laxatives work by drawing water into the intestines and increasing the water content and volume of your stool. As the stool grows in size due to water absorption, it stimulates the intestines and increases the urge to have a bowel movement.
Magnesium oxide is commonly used to treat constipation and is safe to use as a short-term constipation remedy in both adults and children.
A 2021 study found that magnesium oxide supplements were as effective as the herbal laxative senna for treating constipation. The study showed that treatment with 1.5 grams (g) of magnesium oxide per day for 28 days was as effective as daily treatment with 1 gram of senna for improving symptoms of chronic constipation. Both treatments led to significant improvements in the frequency of bowel movements and patient-reported quality of life.
In a 2019 study that included 34 females with chronic constipation, it was found treatment with 1.5 grams of magnesium oxide per day for 28 days led to greater overall improvement of symptoms, including improved spontaneous bowel movement, stool form, abdominal symptoms, and quality of life compared to a placebo treatment. 70.6% of the patients who received magnesium oxide reported overall symptom improvement compared to 25.0% in the placebo group.
Magnesium oxide can be used to treat constipation in children as well.
However, even though magnesium oxide has been shown to be effective for treating constipation, it can lead to high magnesium levels in susceptible populations, such as elderly people and those with medical conditions such as kidney disease.
May Help Promote Healthy Blood Pressure and Blood Sugar Levels
Magnesium is involved in blood sugar and blood pressure regulation and having low magnesium levels may increase the risk of high blood sugar and blood pressure levels.
Taking a magnesium oxide supplement would help boost magnesium levels and improve blood pressure and blood sugar control.
However, although magnesium oxide has been shown to be effective for improving these health outcomes, higher doses may be needed due to its poor absorption rate. For example, a 2021 review of 49 studies noted that only doses of magnesium oxide greater than 600 mg per day were effective for lowering blood pressure in people with untreated high blood pressure.
Magnesium oxide helps lower blood pressure by relaxing smooth muscle cells and dilating blood vessels, which helps improve blood flow.
Magnesium supplementation may also help reduce blood sugar. A 2022 review that included data from 24 studies found that people with diabetes who took magnesium supplements, including magnesium oxide supplements, had significant reductions in fasting blood sugar and the long-term blood sugar control marker HbA1c, as well as reductions in systolic and diastolic blood pressure levels compared to control treatments.
May Improve Stress and Anxiety
Magnesium helps your body regulate and deal with stress and having low magnesium levels has been linked to increased stress and mental health issues, such as anxiety.
Some research suggests that taking magnesium supplements could help relieve stress and improve symptoms of anxiety.
A 2017 review that included 18 studies, four of which studied the effects of magnesium oxide supplements on anxiety, suggested that magnesium supplements could have a beneficial effect on subjective anxiety symptoms. Even though these results are promising, the researchers noted that existing evidence is of poor quality, and more studies are needed to fully understand how magnesium supplements, such as magnesium oxide supplements, may benefit those with anxiety.
Additionally, a 2022 study that included 60 people undergoing open heart surgery found that treatment with 500 mg of magnesium oxide per day for five days helped increase serum magnesium levels and significantly reduced average anxiety and depression levels after surgery compared to a control treatment.
How to Take Magnesium Oxide
Magnesium oxide can be taken at any time of day and is often taken in multiple doses throughout the day.
It can be taken with or without food, but taking it with food could help reduce the risk of gastrointestinal side effects. If you’re using magnesium oxide to treat constipation, it’s recommended that you take the supplement with a full glass of fluids, such as water or juice, and avoid taking magnesium oxide later in the day when your stomach is empty.
When you’re supplementing with magnesium oxide, it’s important that you take other medications at least two hours apart to ensure proper absorption.
Dosage
Dosing for magnesium oxide varies, but doses used in research studies range from 250 mg to 1,000 mg per day.
Keep in mind that higher doses of magnesium oxide should only be taken under the supervision of a healthcare provider, as doses higher than 1,000 mg per day could lead to dangerously high blood levels of magnesium.
If you’re taking magnesium oxide for constipation treatment, you shouldn’t take it for more than one week unless specifically advised and monitored by your doctor.
If you have questions about magnesium oxide dosing, consult a knowledgeable healthcare provider for advice.
Is Magnesium Oxide Safe?
Magnesium oxide is a relatively safe supplement when used in appropriate doses and is commonly used to treat certain medical conditions in adults and children. That said, ingesting large amounts of magnesium oxide supplements can lead to dangerously high blood levels of magnesium, which can cause magnesium toxicity. Magnesium toxicity can cause symptoms such as difficulty breathing, irregular heartbeat, and extremely low blood pressure, and can be fatal.
Although magnesium toxicity is rare and usually due to accidental overdose of magnesium-containing products like laxatives, some people, such as older adults and people with kidney disease, are more at risk for developing magnesium toxicity.
Potential Drug Interactions
Magnesium oxide supplements may interact with the following medications:
Antibiotics: Taking magnesium oxide supplements too close to certain antibiotics, such as doxycycline and ciprofloxacin, could interfere with medication absorption. Antibiotics should be taken two hours before or at least four hours after taking a magnesium oxide supplement.
Blood pressure-lowering medications: Magnesium oxide has been shown to lower blood pressure, especially in high doses. If you’re taking a blood pressure-lowering medication, you should check with your doctor before supplementing with magnesium oxide.
Osteoporosis medications: Magnesium oxide may reduce the absorption of bisphosphonate medications, such as the osteoporosis medication Fosamax. bisphosphonate medications should be taken at least two hours before or after taking magnesium oxide.
It’s also important to be aware that some commonly prescribed medications, such as diuretics, antidiabetic medications, and acid reflux medications, have been shown to deplete magnesium stores. If you’re taking any of these medications, talk to your healthcare provider about adding a magnesium supplement to your diet.
What to Look For
To ensure safety and quality, it’s recommended to purchase dietary supplements, including magnesium supplements, from a reputable manufacturer.
When possible, choose magnesium oxide products certified by organizations like UL, USP, and NSF International, which set strict standards for supplement quality and manufacturing safety.
Magnesium oxide is usually sold in pill or capsule form, but powdered and chewable supplements are also available. Magnesium oxide is one of the most affordable types of magnesium on the market, so it makes a good choice for people who are shopping on a budget.
Can You Take Too Much Magnesium Oxide?
Yes, it’s possible to take too much magnesium oxide. If too much magnesium oxide is ingested, it could cause your blood magnesium to reach toxic levels, which could be life-threatening.
Most cases of magnesium toxicity are related to accidental overdoses, but taking doses over 1,000 mg per day could increase your risk of developing magnesium toxicity. It’s critical to follow recommended dosing protocols and to consult your healthcare provider if you have any questions related to magnesium oxide dosing.
Side Effects of Magnesium Oxide
Magnesium oxide is more likely to cause gastrointestinal side effects than other types of magnesium. Due to its osmotic effects, higher doses of magnesium oxide can trigger symptoms such as:
Nausea
Abdominal pain
If you’re experiencing gastrointestinal side effects when taking magnesium oxide, speak with your healthcare provider. They may recommend lowering the dose of magnesium oxide you’re taking or switching to another form of magnesium that’s gentler on your stomach.
A Quick Review
Magnesium oxide is one of the most common forms of magnesium used in dietary supplements.
Though it has a poor absorption rate, studies show that taking magnesium oxide supplements may help improve symptoms of constipation, ease headaches, reduce blood pressure and blood sugar, and ease anxiety symptoms.
If you’re interested in taking a magnesium oxide supplement, it’s best to speak with your healthcare provider to learn more about appropriate dosing and safe use.
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