Magnesium hydroxide

MineralMagnesium salt

What is it

Magnesium hydroxide is a anti-caking agent and antacid mineral source used in dietary supplement manufacturing. Found on roughly 671 U.S. supplement labels.

How it works

Magnesium hydroxide is added to supplement formulas to support manufacturing, stability, appearance, or delivery rather than to provide a nutritional or physiological benefit. Its role is functional: it helps the active ingredients reach the consumer in a usable form. Excipients of this kind are evaluated for safety at the levels used in finished products, not for any independent biological effect. Most are present in small amounts relative to the active nutrients on the label.

Dosage

There is no recommended intake for Magnesium hydroxide because it is not a nutrient. The amount used is determined by the manufacturer based on the formulation. It typically makes up a small fraction of total product weight.

When and how to take it

Timing is determined by the active ingredient in the supplement, not by Magnesium hydroxide itself. Take the product according to the label or your healthcare provider's instructions.

Safety

Magnesium hydroxide is generally considered safe at the levels typically used in supplements. Many supplement excipients are recognized by the U.S. FDA as Generally Recognized as Safe (GRAS) or are permitted as inactive ingredients. Some consumers prefer to avoid certain excipients on principle, but evidence of harm at the doses found in supplements is limited. People with specific sensitivities or allergies should check labels carefully.

Who should be cautious

People with known allergies or intolerances to Magnesium hydroxide or related compounds should avoid products containing it. There are no specific cautions for pregnancy, breastfeeding, or common medical conditions tied to the small amounts used as a supplement excipient, but anyone with concerns should ask their pharmacist or healthcare provider.

Interactions

No significant interactions reported at the amounts typically present in supplements.

Frequently asked questions

Is Magnesium hydroxide safe in supplements?⌄

At the levels used in dietary supplements, Magnesium hydroxide is generally considered safe. Most supplement excipients are GRAS or have an established safety record for this use.

Why is Magnesium hydroxide in my supplement?⌄

Magnesium hydroxide is added to help with manufacturing, stability, appearance, or how the product is delivered. It does not provide a nutritional effect itself.

Can I avoid Magnesium hydroxide?⌄

Yes. If you'd rather not consume Magnesium hydroxide, read supplement labels carefully and look for products that use different excipients or that are formulated without it.

References

Magnesium hydroxide on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Magnesium hydroxide (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.