What Is Poloxamer 338?
Poloxamer 338 belongs to a family of block copolymers made by linking two water-loving polyethylene oxide chains to a central water-repelling polypropylene oxide chain. This unique structure makes it both attracted to water and oil, a trait prized in skin care formulations. First investigated in the late 1960s for pharmaceutical and household uses, it entered the beauty world during the rise of gentle, rinse-off cleansers in the 1980s when brands searched for non-irritating surfactants.
The ingredient is created through controlled, sequential polymerization: propylene oxide is polymerized around a starter molecule to form the middle block, then ethylene oxide is added to each end until the desired molecular weight is reached. The resulting white, waxy solid or flakes dissolve easily in water and form clear solutions.
Today you will most often spot Poloxamer 338 in micellar waters, facial cleansers, makeup removers, shampoos, bath gels, baby washes, refreshing facial mists and some wipe solutions. Its ability to keep oil and water evenly mixed also lets formulators use it in lightweight moisturizers, aftershave lotions and hydrogel masks where a clean, non-greasy skin feel is essential.
Poloxamer 338’s Cosmetic Benefits/Uses
When added to personal care products Poloxamer 338 performs two key jobs that improve texture and skin feel while helping the formula do its work.
- Cleansing: Its amphiphilic structure surrounds dirt, excess sebum and makeup, lifting them off the skin or hair so they rinse away without the need for harsh sulfates. This leads to milder cleansers suitable for sensitive skin or daily use.
- Emulsifying: By bridging oil and water phases, it stabilizes lotions, gels and micellar solutions, preventing separation over time and delivering a uniform dose of active ingredients with each use.
Who Can Use Poloxamer 338
Poloxamer 338 works well for every skin type, including oily, combination, dry and sensitive skin, because it rinses clean without leaving a residue or disrupting the skin’s natural barrier. People with very dry or compromised skin may wish to pair it with a richer moisturizer, as its thorough cleansing action can leave skin feeling light but not necessarily hydrated.
The ingredient is synthetic and produced without animal derivatives, so it is suitable for both vegans and vegetarians. Because it is nonionic and generally inert, it rarely conflicts with other actives and fits easily into most routines.
Current safety data show no specific risks for pregnant or breastfeeding women when products containing Poloxamer 338 are used as directed. This is not medical advice and anyone who is pregnant or nursing should discuss their skincare choices with their healthcare provider to be on the safe side.
Poloxamer 338 does not increase photosensitivity, so there is no added need for special sun precautions beyond daily SPF use. It is also odorless, making it a good option for those who avoid fragrances or have scent sensitivities.
Potential Side Effects/Adverse Reactions
Side effects from topical Poloxamer 338 vary from person to person. The points below outline potential reactions, though they are uncommon when the ingredient is formulated correctly and used as intended.
- Mild skin dryness
- Temporary tight feeling immediately after rinsing
- Rare cases of redness or irritation in extremely sensitive individuals
- Eye stinging if cleanser is not fully rinsed away
If any discomfort or irritation occurs stop using the product and consult a healthcare professional if symptoms persist.
Comedogenic Rating
Rating: 0 (non-comedogenic)
Poloxamer 338 is a large, water-soluble molecule that rinses off cleanly without lingering on the skin or clogging pores. It lacks the heavy oils or waxes that typically trap dead cells and sebum in follicles, which is why formulators reach for it in lightweight cleansers and micellar waters aimed at breakout-prone complexions. For this reason it is generally considered safe for those who are prone to acne or congestion.
Because it is both nonionic and highly hydrophilic, it does not interact with skin lipids in a way that would encourage comedone formation. Clinical and anecdotal reports rarely link poloxamers to acne flare-ups, making Poloxamer 338 a reliable choice in low-residue rinse-off products.
Summary
Poloxamer 338 is valued in cosmetics for two core jobs: it gently cleanses by surrounding and lifting away oil and debris, and it emulsifies by keeping water and oil phases blended so products stay smooth and stable. Its block-copolymer structure gives it a water-loving exterior and an oil-loving center, letting it shuttle grime into rinse water while leaving skin fresh.
You will most often see it in modern micellar waters, gel cleansers, baby washes and other rinse-off formulas, though it pops up in some lightweight lotions and masks as well. While not a household name like glycerin or hyaluronic acid, its quiet popularity has grown with the rise of sulfate-free and sensitive-skin products.
Current research and global regulatory reviews rate Poloxamer 338 as low risk with minimal irritation potential when used as directed. As with any new product, it is wise to perform a quick patch test to make sure your skin agrees with the full formula.