What Is Poloxamer 331?
Poloxamer 331 is a synthetic, nonionic surfactant made by linking together blocks of propylene oxide and ethylene oxide in a fixed 7 to 54 ratio. This block structure gives the ingredient a water-loving outer portion and an oil-loving core, allowing it to interact with both oil and water. The raw materials—propylene oxide and ethylene oxide—can be sourced from petroleum or from plant-derived feedstocks such as corn or sugarcane, but the finished polymer is always created in a controlled industrial setting.
The first poloxamers were introduced in the 1950s by chemists looking for gentle alternatives to the harsher soaps of the time. Over the following decades formulators discovered that different block sizes gave each poloxamer a unique balance of mildness, foaming and solubility. Poloxamer 331’s particular block length made it especially good at lifting away debris without stripping skin, so it found a home in cosmetics during the 1970s and has remained a staple ever since.
Manufacturing begins with a starter molecule, often a small glycol. Propylene oxide is added first to build the internal hydrophobic block, then ethylene oxide is added to create the outer hydrophilic chains. Temperature, pressure and time are carefully controlled to hit the exact block lengths required for the 7:54 structure. After polymerisation the product is purified, dried and milled into a fine powder or granule that dissolves easily in water.
Thanks to its mild nature you will spot poloxamer 331 in facial cleansers, micellar waters, eye makeup removers, shampoos, shower gels, baby washes, sheet-mask essences, lightweight moisturisers and even some leave-on serums where a bit of gentle cleansing or emulsion stability is needed.
Poloxamer 331’s Cosmetic Benefits/Uses
In a formula poloxamer 331 brings a short list of dependable strengths that make life easier for both the chemist and the user.
- Cleansing: As a mild surfactant it surrounds oil, sunscreen, pollution particles and makeup, lifting them away from skin or hair when rinsed. Because it is nonionic it tends to be less irritating and less likely to disturb the skin barrier than traditional soaps.
- Emulsifying: Its dual-nature block structure helps oil and water stay blended, preventing creams and lotions from separating and giving products a smoother, lighter feel.
Who Can Use Poloxamer 331
Poloxamer 331 is considered gentle enough for all skin types, including oily, dry, combination and sensitive skin, because it cleans without stripping natural oils or leaving a heavy residue. People with highly reactive or compromised skin usually tolerate it well, though as with any ingredient, individual sensitivity can vary.
The polymer is fully synthetic and contains no animal derived substances, so it is suitable for both vegans and vegetarians. Animal testing policies depend on local regulations and the finished brand, but the ingredient itself has no inherent animal connections.
Existing safety assessments list poloxamers as low risk for pregnancy or breastfeeding when used at typical cosmetic concentrations. Still, this is not medical advice and anyone who is pregnant or nursing should discuss new skincare products with a qualified healthcare provider.
Poloxamer 331 does not make skin more sensitive to sunlight, so it will not increase the likelihood of sunburn or hyperpigmentation. It also has no known conflicts with common actives such as retinoids or acids, making it easy to layer within a routine.
Potential Side Effects/Adverse Reactions
Reactions to topical Poloxamer 331 vary from person to person. The points below list potential issues, but most users will not experience them when the ingredient is used correctly in a well-formulated product.
- Mild skin irritation A small number of individuals may notice transient redness or itching, especially if the product is left on the skin for an extended period instead of being rinsed
- Eye stinging Direct contact with the eyes can cause temporary watering or discomfort until the area is flushed with clean water
- Dryness Excessively high concentrations or very frequent cleansing may strip some moisture leading to tightness or flaking
- Allergic contact dermatitis Extremely rare cases of allergy have been documented with poloxamers, presenting as persistent redness, rash or swelling
Discontinue use and consult a medical professional if any adverse reaction develops while using Poloxamer 331 or products that contain it.
Comedogenic Rating
Rating: 0
Poloxamer 331 is highly water soluble and forms micelles that rinse away cleanly instead of sitting in pores, so it does not trap oil or dead cells that could spark breakouts. Because it is nonionic it also avoids the film-forming residue that some surfactants leave behind.
Suitable for acne-prone and breakout-prone skin.
No studies have linked poloxamers with fungal acne triggers, making them a safe choice for those managing Malassezia-related concerns.
Summary
Poloxamer 331 mainly acts as a gentle cleanser and an emulsifier. Its block structure has an oil-loving core that grabs dirt, makeup and excess sebum while the water-loving ends keep everything suspended until you rinse. In creams it positions itself at the oil-water interface, stopping separation and giving formulas a light silky feel.
It is not a headline ingredient like hyaluronic acid or niacinamide, but chemists reach for it often so you will quietly find it in many mainstream cleansers, micellar waters and lotions.
Current safety reviews rate poloxamer 331 as low risk with minimal irritation potential at normal use levels. Still, skin is personal so patch testing any new product is a smart extra step.