Magnesium Oxide
Mineral
Also known as: MgO, Milk of magnesia
A
Grade A💊 400-500 mg (only ~20mg absorbed)🎯 4 primary uses🔗 1 synergy⚠️ Review warnings
Levels upNutrition+50 pts
Overview
High elemental magnesium content but poor absorption (4%). Primarily useful as a laxative; not ideal for Mg repletion.
Primary Uses
LaxativeBasic magnesium supplementationConstipationStrong laxative effect
Frequently Asked About Magnesium Oxide
How much Magnesium Oxide should I take?
The typical effective range is 400-500 mg (only ~20mg absorbed). Individual needs vary based on age, body weight, diet, and goals — start at the lower end and adjust based on response. Always consult a healthcare provider before starting a new supplement.
When is the best time to take Magnesium Oxide?
Any. Consistency matters more than perfect timing — pick a daily anchor (e.g. with breakfast or before bed) and stick with it.
Should I take Magnesium Oxide with food?
Optional.
Does Magnesium Oxide interact with medications?
Yes — known interactions include Standard. If you take any prescription medication, talk to your doctor or pharmacist before starting Magnesium Oxide.
What does Magnesium Oxide pair well with?
Magnesium Oxide stacks well with Consider switching forms — these combinations either improve absorption or work synergistically toward common goals.
Who should not take Magnesium Oxide?
Magnesium Oxide should be avoided or used with caution by people with Kidney disease. Pregnant or breastfeeding women should consult a healthcare provider before use.
What are the side effects of Magnesium Oxide?
Most people tolerate Magnesium Oxide well. The most commonly reported side effects are Diarrhea common. Side effects are usually dose-dependent — lowering the dose often resolves them.
Dosage
Typical range
400-500 mg (only ~20mg absorbed)
Timing
Any
With food
Optional
Duration
Better forms available
Special Populations
Primarily as laxative
Research & Studies
Search the literature now
We haven’t curated landmark studies for Magnesium Oxideyet — one-click into the primary literature here. PubMed (RCTs) is usually the highest-signal starting point.
Mechanism of Action
- • Only 4% absorbed
- • Strong osmotic laxative effect
- • High elemental content per weight
Evidence Quality
Evidence Grade A
Well-established laxative effect
Safety & Contraindications
Serious Warnings
- • Standard Mg
Contraindications
- • Kidney disease
Common Side Effects
- • Diarrhea common
Pregnancy & Breastfeeding
Consult healthcare provider
Liver & Kidney Notes
Avoid kidney disease
Interactions
💊 Medications
- • Standard
🧪 Supplements
- • Better forms preferred
🍽️ Food & Alcohol
- • No interactions
Stacking & Synergies
Pairs Well With
Consider switching forms
Avoid Combining With
Better absorbed forms available
Best Goal Synergies
Laxative only
Buying Guide
What to Look For
- • Consider better absorbed forms
Standardization Markers
Elemental Mg
Adulteration risk
Low
Practical Notes
- • Only 4% absorbed
- • Better forms available for Mg repletion
- • Strong laxative effect
- • Stay hydrated
- • Not best for magnesium supplementation
Tags
minerallaxativelow absorptionosmoticmagnesiumstrong
Related Guides
In-depth guides covering Magnesium Oxide — protocols, comparisons, and use cases.
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Trace mineral supporting bone health, cognitive function, and hormone metabolism. May support testosterone in deficient states.
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Essential mineral for bone health, muscle function, nerve signaling, and blood clotting.
Calcium Carbonate
Common, economical calcium form with highest elemental calcium percentage. Requires stomach acid for absorption.
Calcium Citrate
Well-absorbed calcium form that doesn't require stomach acid. Better for those on acid-reducing medications.
Chloride
Essential electrolyte mineral that works with sodium and potassium to maintain fluid balance, nerve transmission, and stomach acid production.
Chromium Picolinate
Trace mineral for insulin sensitivity and blood sugar regulation. Popular for carb cravings.
Last reviewed: June 2026 by the Formulate Research Team. Sources cited above; methodology and scoring criteria published here.
Cite this page
Formulate Research Team. (2026, June). Magnesium Oxide — Evidence-Based Supplement Guide. Formulate Supplement Encyclopedia. https://app.formulate-health.app/learning/supplements/magnesium-oxide
Educational content based on published research and our scoring methodology. Not medical advice — consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you take medications, are pregnant, or have a medical condition.