Ingredient review

Magnesium Hydroxide

INCI: Magnesium Hydroxide

Magnesium hydroxide is a gentle mineral pH adjuster and oil absorber, but can be drying for some skin types.

beautyskincarepH adjuster

In plain English

Magnesium hydroxide is a white, powdery mineral that helps control the acidity (pH) of skincare products. It can also soak up extra oil on your skin, which is why it's sometimes used in cleansers and masks for oily or acne-prone skin. Think of it as a mild, non-drying version of baking soda for your face.

Review score

Safety, usefulness, and evidence

3.8Good
3.8/ 5

Potentially useful with some tradeoffs

The evidence base is useful, but some claims depend heavily on the formula.

Main practical flags: irritation is moderate; clogging risk is low.

Source
natural
Evidence
moderate
Irritation
moderate
Clogging risk
low
How reviews are scored

Quick decision guide

Useful, but context matters

Magnesium Hydroxide can be useful, but watch for some irritation potential.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Magnesium Hydroxide.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

moderate

Can bother some users, especially with frequent use, damaged skin, or strong companion ingredients.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

Magnesium hydroxide is an inorganic compound made from magnesium, oxygen, and hydrogen. In cosmetics, it's used as a pH adjuster to keep formulas stable and gentle, and as an absorbent to reduce shine.

How it works

It works by neutralizing acids in a formula, raising the pH to a desired level (usually slightly alkaline). On the skin, it can bind to excess sebum and impurities, helping to remove them when rinsed off. It does not actively treat acne or oil production, but it can temporarily mattify the skin.

Pros

Gentle pH balancer

Helps keep skincare formulas at a skin-friendly pH without harsh acids or alkalis, reducing the risk of irritation.

Effective oil absorber

Quickly soaks up surface oil and shine, making it useful in mattifying masks or cleansers for oily skin.

Cons and cautions

Can be drying

In high concentrations or frequent use, it may strip natural oils, leading to tightness or flakiness, especially for dry skin.

Temporary effect only

Does not address the root cause of oiliness or acne, so results are temporary and may not satisfy those seeking long-term control.

Best for

  • People with oily or combination skin
  • Those looking for a gentle pH adjuster in cleansers or masks

Use caution if

  • Individuals with very dry or dehydrated skin
  • Anyone with eczema or active skin barrier damage

Usage tips

Use in a rinse-off product like a mask or cleanser, not a leave-on formula, to minimize drying.
Start with a low-concentration product if you have sensitive or dry skin, and patch test first.

Safety summary

Generally safe for topical use in cosmetics at low concentrations. High concentrations or prolonged contact may cause dryness or mild irritation. Avoid use on broken or irritated skin.

Research notes

Research supports its use as a safe pH adjuster and absorbent. No peer-reviewed studies show it effectively treats acne or oil production long-term. Its safety is well-established by cosmetic ingredient review panels.

Common label clues

Typical concentration
0.5% to 5%
Regulatory status
Approved for use in cosmetics by the FDA and EU CosIng database as a safe pH adjuster and absorbent within typical concentrations.
Common uses
Cleansers, Masks, Deodorants
Environmental note
Magnesium hydroxide is a naturally occurring mineral, mined or synthesized with low environmental impact, and is biodegradable.

Good to know

  • Magnesium hydroxide is also known as milk of magnesia when suspended in water, but cosmetic-grade versions are purified for skin use.
  • It is not the same as magnesium oxide or magnesium sulfate (Epsom salts).

Common questions

What is Magnesium Hydroxide in beauty products?

Magnesium hydroxide is a white, powdery mineral that helps control the acidity (pH) of skincare products. It can also soak up extra oil on your skin, which is why it's sometimes used in cleansers and masks for oily or acne-prone skin. Think of it as a mild, non-drying version of baking soda for your face.

What does Magnesium Hydroxide do in a beauty product?

It works by neutralizing acids in a formula, raising the pH to a desired level (usually slightly alkaline). On the skin, it can bind to excess sebum and impurities, helping to remove them when rinsed off. It does not actively treat acne or oil production, but it can temporarily mattify the skin.

Is Magnesium Hydroxide safe for most people?

Generally safe for topical use in cosmetics at low concentrations. High concentrations or prolonged contact may cause dryness or mild irritation. Avoid use on broken or irritated skin.

Who should be careful with Magnesium Hydroxide?

Individuals with very dry or dehydrated skin Anyone with eczema or active skin barrier damage

Research sources

CosIng Database - Magnesium HydroxideOpenFDA - Generally Recognized as Safe (GRAS)OpenPubMed - Safety of Magnesium Hydroxide in CosmeticsOpen

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.