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Minerals & electrolytes

Magnesium Hydroxide

Magnesium Hydroxide

Magnesium hydroxide, also called magnesium dihydroxide, is an inorganic magnesium compound. A 2024 systematic review found insufficient randomized evidence to draw conclusions about magnesium supplements and cognitive health; it does not establish a cognitive benefit for magnesium hydroxide. Compare any listing by active ingredient, intended use, label warnings, and price per labeled amount; this profile currently has no mapped offers.

Mineral SaltForm Dependent EvidenceLow Risk ProfileGi Side EffectsKidney CautionMedication Interaction RiskDose Sensitive
Updated August 2026/5 min read/4 citations
Reviewed by the NootropicsIndex editorial team.Method: prioritize cited human research and official safety or regulatory sources; compare retailer-listed prices without endorsing products.Affiliate disclosure
Extra caution

Who should avoid this or get expert review first

This is not a recommendation to use. These groups should treat the profile as a reason to slow down and verify safety, rules, and personal context.

  • SEEK CLINICAL ADVICE2Current U.S. OTC labels advise asking a doctor before use with kidney disease, a magnesium-restricted diet, stomach pain, nausea, vomiting, or a prolonged bowel-habit change. The label also advises professional input during pregnancy or breastfeeding. These are label-specific safeguards, not individualized medical advice.
Supplement form

Magnesium Hydroxide is a form of Magnesium

View all Magnesium productsMagnesium AspartateMagnesium CarbonateMagnesium ChlorideMagnesium CitrateMagnesium GluconateMagnesium GlycinateMagnesium LactateMagnesium L-ThreonateMagnesium MalateMagnesium OrotateMagnesium OxideMagnesium PidolateMagnesium SulfateMagnesium Taurate
01

What is it?

What the cognition evidence does and does not show

4

A 2024 systematic review found three randomized trials and concluded that the limited randomized evidence was insufficient to draw conclusions about magnesium supplements and cognitive health. That broad evidence does not establish a cognitive benefit for magnesium hydroxide specifically.

What Magnesium Hydroxide is

1

Magnesium hydroxide (Mg(OH)2) is an inorganic magnesium compound also called magnesium dihydroxide.

Compare intended use before price2
An oral magnesium hydroxide product can be an OTC medicine rather than a general-purpose nootropic supplement. Compare active ingredient, labeled intended use, warnings, serving format, and price per labeled amount before considering listings comparable.
02

Mechanisms of action

Gastrointestinal activity, not a brain-targeted mechanism

3

NIH ODS explains that the laxative effects of unabsorbed magnesium salts arise from osmotic activity in the intestine and colon and stimulation of gastric motility. That gastrointestinal mechanism is not evidence of a cognitive mechanism or nootropic effect.

03

Potential effects and evidence map

A 2024 systematic review found three randomized trials and insufficient evidence to draw conclusions about magnesium supplements and cognitive health. It does not establish a cognitive benefit for magnesium hydroxide specifically.

Effect domainMagnitudeGrade
Focus / attention4
UnknownConfidence: High

No direct human evidence establishes magnesium hydroxide as an attention or focus enhancer.

Note The systematic review found insufficient randomized evidence for magnesium supplements and cognitive health; it does not establish a magnesium-hydroxide-specific attention outcome.

0/5
E
Cellular / long-term brain support4
UnknownConfidence: High

No direct human evidence establishes magnesium hydroxide as a long-term brain-support intervention.

Note General magnesium nutrition information should not be converted into a form-specific nootropic claim.

0/5
E
04

Typical dosages and timing

U.S. OTC LABEL22.4 g/30 mL

One current U.S. label lists 2.4 g of magnesium hydroxide in each 30 mL. This is an ingredient-strength example, not a nootropic dose or a general-use recommendation; no validated cognitive dose or cycle is established.

05

Timing & effect horizon

Effect horizonUnknown
Unknown
Label timing is gastrointestinal, not cognitive2

One current U.S. saline-laxative label says a bowel movement generally occurs in one-half to six hours. This is a product-label gastrointestinal timing statement, not an onset or duration for cognitive effects.

06

Safety, side effects and risk profile

GI discomfort2
Confidence: High

Oral magnesium hydroxide products are labeled for antacid or saline-laxative use; GI effects are central to that product context.

Note Do not treat laxative-label use as a nootropic regimen.

3/5
A
Liver / kidney caution2
Confidence: High

Current U.S. OTC labels advise asking a doctor before use with kidney disease or a magnesium-restricted diet.

Note This is a label-specific higher-risk context, not a statement that healthy adults have the same base risk.

3/5
A
Interaction risk3
Confidence: High

Magnesium can reduce absorption of certain oral antibiotics and bisphosphonates.

Note Use medicine-specific timing instructions from the label, pharmacist, or prescriber.

3/5
A
COMMON PRACTICAL ISSUE3

High magnesium intake from supplements or medicines can cause diarrhea, nausea, and abdominal cramping. Magnesium hydroxide's labeled saline-laxative context makes gastrointestinal effects especially important when assessing product fit.

07

Interactions and cautions

MEDICINE-SPECIFIC SPACING3

Magnesium can reduce absorption of oral bisphosphonates and can form complexes with tetracycline or quinolone antibiotics. Follow the relevant medicine label and confirm timing with a pharmacist or prescriber rather than applying a generic supplement schedule.

08

Legal and regulatory status

UNITED STATES - AS OF 20262

As of 2026, current DailyMed records include oral magnesium hydroxide suspensions classified as human OTC drug labels for antacid and saline-laxative use. This does not establish the status of every product or other markets; intended use, labeling, and local rules determine the applicable requirements.

09

How it compares

FORM COMPARISON3

Magnesium hydroxide is a distinct magnesium form with an OTC gastrointestinal-use context. General magnesium nutrition information and claims about other salts do not automatically transfer to this form, so compare the named compound, intended use, elemental amount, safety context, and normalized price.

10

Practical buying and quality notes

  • This profile currently has no mapped active offers, so it cannot show a reliable live price comparison. If offers are added, compare the exact active ingredient, product category, labeled amount, servings, region, shipping, and total checkout cost rather than assuming all magnesium products are interchangeable.2
11

FAQ

Is Magnesium Hydroxide a nootropic?

4

A 2024 systematic review found insufficient randomized evidence to draw conclusions about magnesium supplements and cognitive health. It did not establish magnesium hydroxide as an enhancer of focus, memory, or other cognitive outcomes.

How should Magnesium Hydroxide prices be compared?

2

Compare only products with the same active ingredient and intended use. Then normalize by labeled amount, number of servings, formulation, region, shipping, and total cost. This profile has no active mapped offers yet.

Can evidence for one magnesium form be assumed for another?

4

No. The available magnesium cognition literature is not enough to establish a universal benefit across magnesium supplements, so product identity and direct evidence should be checked for the exact compound and intended use.

12

References

  1. National Center for Biotechnology Information. PubChem Compound Summary: Magnesium Hydroxide (CID 73981).
  2. DailyMed. Milk of Magnesia: magnesium hydroxide oral suspension, human OTC drug label.
  3. National Institutes of Health Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals.
  4. Chen F, Wang J, Cheng Y, et al. Magnesium and Cognitive Health in Adults: A Systematic Review and Meta-Analysis. Adv Nutr. 2024;15(8):100272.
Note

This page is informational and summarizes available evidence. It is not medical advice, a recommendation, or a substitute for guidance from a qualified clinician.