Why is magnesium oxide side effects Better?

30 Jun.,2025

 

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

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Magnesium Oxide: 5 Benefits, Uses, Side Effects, and More - Health

Magnesium oxide is one of the most common types of magnesium used in dietary supplements. It has lower bioavailability than other forms of magnesium, but it may have benefits for headache and constipation relief.

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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 in dietary supplements. You can find it in multi-nutrient supplements, such as multivitamins and multimineral supplements, as well as in magnesium-only supplements. 

1. May Reduce Headaches

Magnesium oxide may treat headaches, including migraines. It prevents the excessive activation of excitatory neurotransmitters, which are chemical messengers. This action inhibits pro-inflammatory pathways, increases blood vessel dilation, and improves blood flow to the brain.

One study found that 500 milligrams of magnesium oxide per day for eight weeks reduced migraine attacks, similar to the migraine medication valproate sodium.

Magnesium oxide is generally safe, with fewer side effects than headache medications, and is safe during pregnancy. One study found magnesium oxide, alone or combined with riboflavin, reduced migraine frequency, severity, and duration in 203 pregnant people. Of the 154 people who reported migraine symptoms, 77% had improvement after magnesium treatment.

2. Helps Treat Constipation 

Magnesium oxide is an osmotic laxative that draws water into your intestines, which increases stool volume and stimulates bowel movements. It's commonly used as a safe short-term constipation treatment in adults and children but can be unsafe in older adults and those with kidney disease.

One study found that 1.5 grams of magnesium oxide per day for 28 days was as effective as 1 gram of the herbal laxative senna in improving chronic constipation.

Another study showed that 1.5 grams of magnesium oxide per day for 28 days improved bowel movements, stool form, abdominal (belly) symptoms, and quality of life. About 70% of participants reported symptom improvement compared to 25% in the placebo group.

3. Helps Manage Blood Pressure

Having low magnesium levels may increase the risk of hypertension (high blood pressure). Magnesium oxide helps relax smooth muscle cells and dilate blood vessels to improve blood flow and lower blood pressure.

You may need high doses of magnesium oxide to regulate blood pressure due to its poor absorption rate. One review of 49 studies found that only doses of magnesium oxide greater than 600 milligrams per day effectively lowered blood pressure in people with untreated hypertension.

4. Might Lower Blood Sugar

Magnesium oxide supplementation may reduce blood sugar. One review of 24 studies looked at people with diabetes who took magnesium supplements, including magnesium oxide. The participants had significant reductions in fasting blood sugar and HbA1c, or a long-term blood sugar control marker.

5. May Improve Stress and Anxiety

Magnesium helps your body regulate stress. Low magnesium levels have been shown to increase stress and anxiety. Some evidence suggests that magnesium oxide supplementation could relieve stress and improve anxiety symptoms.

One review of 18 studies, including four on magnesium oxide, found that magnesium supplements could alleviate anxiety symptoms. The authors noted that the evidence was of poor quality, so more studies are needed.

For more information, please visit magnesium oxide side effects.

Another study found that 500 milligrams of magnesium oxide per day for five days reduced anxiety and depression levels after open heart surgery compared to a control treatment.

Medically reviewed by Mary Choy, MD

How To Take

You can take magnesium oxide at any time of day or in multiple doses throughout the day. Taking it with food could reduce the risk of gastrointestinal side effects. It's recommended that you take magnesium oxide with a full glass of fluids if you use it to treat constipation.

Avoid taking it later in the day when your stomach is empty. You should not take magnesium oxide for more than one week for constipation unless a healthcare provider advises and monitors you.

Dosage 

The recommended dose for magnesium oxide varies. Only take higher doses of magnesium oxide under the supervision of a healthcare provider. Doses higher than 1,000 milligrams a day could lead to dangerously high magnesium levels. Consult a knowledgeable healthcare provider for advice if you have questions about magnesium oxide dosing.

Is Magnesium Oxide Safe?

Magnesium oxide is relatively safe in adults and children when you use it in appropriate doses. Ingesting large amounts of magnesium oxide can lead to dangerously high levels, which can cause magnesium toxicity. Symptoms include difficulty breathing, irregular heartbeat, extremely low blood pressure, and even death. Magnesium toxicity is rare and usually due to accidental overdose. Some people, such as older adults and those with kidney disease, are more at risk.

Potential Drug Interactions

Magnesium oxide supplements may interact with the following medications:

  • Antibiotics: Taking magnesium oxide too close to antibiotics, such as doxycycline and ciprofloxacin, could interfere with absorption. Take antibiotics two hours before or at least four hours after taking magnesium oxide.
  • Blood pressure medications: Magnesium oxide has been shown to lower blood pressure, especially in high doses. Check with a healthcare provider before supplementing with magnesium oxide if you take a medication to lower blood pressure.
  • Bisphosphonates: Magnesium oxide may reduce the absorption of bisphosphonates that treat osteoporosis, such as Fosamax (alendronic acid). Take bisphosphonates at least two hours before or after magnesium oxide.

Some commonly prescribed medications, such as diuretics, diabetes medications, and acid reflux drugs, have been shown to deplete magnesium stores. Talk to a healthcare provider about starting a magnesium supplement if you take any of these.

What To Look For 

Magnesium oxide is usually sold in pill or capsule form. 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?

It's possible to take too much magnesium oxide. 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. Taking doses over 1,000 milligrams a day could increase your risk of magnesium toxicity. Follow recommended dosing protocols and consult a healthcare provider if you have any questions about 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 can trigger symptoms like:

  • Abdominal pain
  • Diarrhea
  • Nausea

Speak with a healthcare provider if you develop gastrointestinal side effects from magnesium oxide. They may recommend lowering the dose or switching to a gentler form of magnesium on your stomach.

A Quick Review

Magnesium oxide is one of the most common forms of magnesium used in dietary supplements. It has a poor absorption rate, but magnesium oxide may have benefits for headache and constipation relief. It's best to speak with a healthcare provider to learn more about appropriate dosing and safe use if you want to take magnesium oxide.

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