Ingredient review
Glycereth-18
INCI: GLYCERETH-18
A gentle, water-attracting ingredient that helps keep skin hydrated without feeling sticky or heavy.
In plain English
Glycereth-18 is a modified version of glycerin, a common moisturizing ingredient. The modification makes it even better at holding onto water and spreading smoothly on the skin. It works by pulling moisture from the air into the outer layer of your skin, helping it stay soft and hydrated. Because it's water-soluble and non-greasy, it's often used in lightweight gels, serums, and lotions for all skin types, including oily and acne-prone skin.
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-18 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-18.
- 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-18 is a polyethylene glycol (PEG) derivative of glycerin. It is created by adding 18 ethylene oxide units to glycerin, which increases its water solubility and reduces its stickiness compared to plain glycerin. It appears as a clear, viscous liquid and is widely used in cosmetics as a humectant and skin-conditioning agent.
How it works
Glycereth-18 attracts water molecules from the environment and binds them to the skin's surface, a process called humectancy. Its larger molecular structure (due to the ethoxylation) helps it form a thin, even film on the skin that holds moisture without feeling tacky. This film also helps other ingredients spread more evenly and can improve the texture of a product.
Pros
Lightweight hydration
Unlike plain glycerin, Glycereth-18 feels less tacky on the skin, making it ideal for gel-based and oil-free moisturizers.
Low irritation potential
It has a low irritation and comedogenic rating, so it's generally safe for sensitive and acne-prone skin.
Cons and cautions
Humidity-dependent
In very dry environments, humectants like Glycereth-18 can draw moisture from the deeper layers of skin if not sealed with an occlusive, potentially causing dryness.
Processing concerns
As an ethoxylated ingredient, trace amounts of 1,4-dioxane (a potential contaminant) can form during manufacturing, though reputable brands use purification steps to keep levels within safe limits.
Best for
- Anyone looking for a lightweight, non-sticky hydrating ingredient
- People with oily or combination skin who want moisture without heaviness
- Those with sensitive skin who tolerate glycerin well
Use caution if
- Individuals with known allergies to PEG compounds (rare)
Usage tips
Safety summary
Glycereth-18 is considered safe for cosmetic use at typical concentrations. It has low irritation and comedogenic potential. The main safety consideration is the potential for trace 1,4-dioxane contamination, but cosmetic-grade ingredients are purified to meet safety standards.
Research notes
Research on Glycereth-18 specifically is limited, but it is well-established as a safe humectant based on its similarity to other PEG glycerin derivatives. The Cosmetic Ingredient Review (CIR) panel has reviewed ethoxylated glycerins and found them safe for use in cosmetics.
Common label clues
- Typical concentration
- Typically 0.5–5% in leave-on products; up to 10% in rinse-off products
- Regulatory status
- Approved for use in cosmetics in the US, EU, and many other regions. The Cosmetic Ingredient Review (CIR) panel has deemed it safe at concentrations up to 10%.
- Common uses
- Serums, Moisturizers, Cleansers, Toners
- Environmental note
- As a PEG derivative, Glycereth-18 may have moderate biodegradability. Some consumers prefer non-ethoxylated alternatives for environmental reasons.
Good to know
- Glycereth-18 is often used in combination with other humectants like glycerin or hyaluronic acid for enhanced hydration.
- It is considered safe by the Cosmetic Ingredient Review (CIR) panel at typical use concentrations.
Common questions
What is Glycereth-18 in beauty products?
Glycereth-18 is a modified version of glycerin, a common moisturizing ingredient. The modification makes it even better at holding onto water and spreading smoothly on the skin. It works by pulling moisture from the air into the outer layer of your skin, helping it stay soft and hydrated. Because it's water-soluble and non-greasy, it's often used in lightweight gels, serums, and lotions for all skin types, including oily and acne-prone skin.
What does Glycereth-18 do in a beauty product?
Glycereth-18 attracts water molecules from the environment and binds them to the skin's surface, a process called humectancy. Its larger molecular structure (due to the ethoxylation) helps it form a thin, even film on the skin that holds moisture without feeling tacky. This film also helps other ingredients spread more evenly and can improve the texture of a product.
Is Glycereth-18 safe for most people?
Glycereth-18 is considered safe for cosmetic use at typical concentrations. It has low irritation and comedogenic potential. The main safety consideration is the potential for trace 1,4-dioxane contamination, but cosmetic-grade ingredients are purified to meet safety standards.
Who should be careful with Glycereth-18?
Individuals with known allergies 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.