Ingredient review
Sodium Hydroxymethane Sulfonate
INCI: SODIUM HYDROXYMETHANE SULFONATE
A synthetic stabilizer that helps preserve formulas and prevent color changes, but may release trace formaldehyde under certain conditions.
In plain English
Sodium hydroxymethane sulfonate is a lab-made ingredient that helps keep your skincare products fresh and prevents them from changing color over time. It works by releasing tiny amounts of a preservative molecule called formaldehyde, which stops bacteria and mold from growing. The amount released is very small and considered safe by regulators, but some people prefer to avoid any formaldehyde-related ingredients.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Sodium Hydroxymethane Sulfonate is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Sodium Hydroxymethane Sulfonate.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- 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
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A synthetic sulfonate salt used as a preservative booster and antioxidant in cosmetics. It is chemically related to formaldehyde but is designed to release it slowly and at very low levels.
How it works
It slowly breaks down in the product to release small amounts of formaldehyde, which acts as a preservative by killing or inhibiting microbes. It also helps prevent oxidation that can cause discoloration or rancidity in formulas.
Pros
Effective preservative booster
Helps keep products fresh and free from microbial growth, extending their usable life.
Prevents discoloration
Stops formulas from turning yellow or brown over time, keeping them looking as intended.
Cons and cautions
Formaldehyde release
Can release trace amounts of formaldehyde, which may cause irritation or allergic reactions in sensitive individuals.
Synthetic origin
Not natural or plant-derived, which may be a concern for those seeking clean or natural beauty products.
Best for
- People using products that need extra preservation
- Those who want to prevent their products from changing color
Use caution if
- Anyone with a known formaldehyde allergy or sensitivity
- People who prefer completely formaldehyde-free formulations
Usage tips
Safety summary
Considered safe for most people at typical cosmetic concentrations. However, it may release trace formaldehyde, so those with allergies or sensitivities should avoid it.
Research notes
Studies show it is an effective preservative booster. The Cosmetic Ingredient Review panel concluded it is safe when formulated to release no more than 0.2% formaldehyde.
Common label clues
- Typical concentration
- 0.1% to 1%
- Regulatory status
- Approved for use in cosmetics in the US and EU at concentrations up to 0.2% (as formaldehyde equivalent). Always follow local regulations.
- Common uses
- Cleansers, Shampoos, Conditioners, Leave-on products
- Environmental note
- Synthetic ingredient; not biodegradable in all conditions. Minimal environmental impact at low use levels.
Good to know
- Sodium hydroxymethane sulfonate is sometimes listed under the alias sodium formaldehyde sulfoxylate on labels.
- Regulatory bodies like the Cosmetic Ingredient Review (CIR) have deemed it safe at typical use levels.
Common questions
What is Sodium Hydroxymethane Sulfonate in beauty products?
Sodium hydroxymethane sulfonate is a lab-made ingredient that helps keep your skincare products fresh and prevents them from changing color over time. It works by releasing tiny amounts of a preservative molecule called formaldehyde, which stops bacteria and mold from growing. The amount released is very small and considered safe by regulators, but some people prefer to avoid any formaldehyde-related ingredients.
What does Sodium Hydroxymethane Sulfonate do in a beauty product?
It slowly breaks down in the product to release small amounts of formaldehyde, which acts as a preservative by killing or inhibiting microbes. It also helps prevent oxidation that can cause discoloration or rancidity in formulas.
Is Sodium Hydroxymethane Sulfonate safe for most people?
Considered safe for most people at typical cosmetic concentrations. However, it may release trace formaldehyde, so those with allergies or sensitivities should avoid it.
Who should be careful with Sodium Hydroxymethane Sulfonate?
Anyone with a known formaldehyde allergy or sensitivity People who prefer completely formaldehyde-free formulations
Research sources
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.