Ingredient review
Glycereth-31
INCI: GLYCERETH-31
A gentle, water-loving humectant that helps hydrate the skin without feeling sticky or heavy.
In plain English
Glycereth-31 is a modified version of glycerin, a common moisturizing ingredient. By adding ethylene oxide units (the 'eth' part), it becomes even better at attracting and holding water, and it feels less sticky on the skin. It's often used in water-based products like serums and lotions to boost hydration and improve the product's texture.
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
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Glycereth-31 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 Glycereth-31.
- 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
Glycereth-31 is a polyethylene glycol (PEG) derivative of glycerin, specifically with an average of 31 ethylene oxide units. It is a clear, viscous liquid that is highly water-soluble and functions primarily as a humectant.
How it works
It works by drawing moisture from the air into the outer layer of the skin (the stratum corneum), helping to keep it hydrated. Its larger molecular size compared to plain glycerin means it stays on the skin's surface longer, providing sustained moisture without a tacky feel.
Pros
Lightweight hydration
Provides effective moisture without the heavy, sticky feel that some humectants like plain glycerin can leave behind.
Improves product texture
Helps create a smooth, spreadable consistency in serums and creams, making them more pleasant to apply.
Cons and cautions
Manufacturing concerns
As a PEG compound, it may be produced using ethylene oxide, which is a potentially hazardous chemical. However, finished cosmetic products contain only trace, safe levels.
Humidity dependent
In very dry climates, humectants like Glycereth-31 can sometimes draw moisture from deeper skin layers if not sealed with an occlusive moisturizer.
Best for
- People with normal to dry skin looking for extra hydration
- Those who find plain glycerin too sticky or tacky
Use caution if
- Individuals with known sensitivity to PEG compounds (rare)
Usage tips
Safety summary
Glycereth-31 is considered safe for topical use in cosmetics at typical concentrations. It has a low irritation and comedogenic profile. The main concern is the potential presence of 1,4-dioxane, a byproduct of ethoxylation, but reputable manufacturers purify their ingredients to meet safety standards.
Research notes
The safety of PEG derivatives has been reviewed by the Cosmetic Ingredient Review (CIR) panel, which concluded they are safe for use in cosmetics. Studies show ethoxylated glycerins are effective humectants with low skin irritation potential.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics by the FDA and the European Commission. The Cosmetic Ingredient Review (CIR) panel has deemed PEG derivatives safe for use in cosmetics when formulated properly.
- Common uses
- Serums, Moisturizers, Cleansers, Toners
- Environmental note
- PEG compounds can be biodegradable, but their production involves petrochemicals. Some manufacturers are moving toward bio-based PEG alternatives.
Good to know
- Glycereth-31 is considered a non-comedogenic ingredient, meaning it is unlikely to clog pores.
- It is often used in 'water gel' type formulas for a refreshing, lightweight feel.
Common questions
What is Glycereth-31 in beauty products?
Glycereth-31 is a modified version of glycerin, a common moisturizing ingredient. By adding ethylene oxide units (the 'eth' part), it becomes even better at attracting and holding water, and it feels less sticky on the skin. It's often used in water-based products like serums and lotions to boost hydration and improve the product's texture.
What does Glycereth-31 do in a beauty product?
It works by drawing moisture from the air into the outer layer of the skin (the stratum corneum), helping to keep it hydrated. Its larger molecular size compared to plain glycerin means it stays on the skin's surface longer, providing sustained moisture without a tacky feel.
Is Glycereth-31 safe for most people?
Glycereth-31 is considered safe for topical use in cosmetics at typical concentrations. It has a low irritation and comedogenic profile. The main concern is the potential presence of 1,4-dioxane, a byproduct of ethoxylation, but reputable manufacturers purify their ingredients to meet safety standards.
Who should be careful with Glycereth-31?
Individuals with known sensitivity to PEG compounds (rare)
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.