What Is Buteth-3?
Buteth-3 is the trade name for a synthetic compound that chemists describe as poly(oxy-1,2-ethanediyl) .alpha.-butyl-.omega.-hydroxy- with an average of three ethylene oxide units. In simpler terms it is a small non-ionic molecule created by reacting butyl alcohol with ethylene oxide. This reaction links three tiny “building blocks” of ethylene oxide to the alcohol giving the final ingredient both oily and water-friendly parts.
The ability to mix with water and oil made ingredients like Buteth-3 popular in the 1960s when formulators started looking for safer non-ionic options to replace harsh cleaners. Since then it has stayed in use because it is reliable affordable and easy to blend into many bases. Production today is fully synthetic carried out in closed reactors where temperature and pressure are carefully controlled to attach exactly three ethylene oxide units to each butyl alcohol molecule. After purification the result is a clear liquid that has little odor and mixes readily with most cosmetic raw materials.
You will often spot Buteth-3 in lightweight facial lotions, fluid moisturizers and daily serums where a clean non-greasy feel is important. It also shows up in makeup removers, micellar waters, sheet masks, hair conditioners and some rinse-off cleansers where it helps keep the formula uniform and stable.
Buteth-3’s Cosmetic Benefits/Uses
In cosmetics Buteth-3 serves one key role: it is a solvent. By dissolving both oil-loving and water-loving ingredients it helps blend actives, fragrances and preservatives evenly through a product. This keeps formulas clear, prevents separation and can improve the feel of a cream or liquid on the skin or hair.
Who Can Use Buteth-3
Because Buteth-3 is a small non-ionic solvent with a light feel it is generally considered suitable for all skin types including oily dry combination and sensitive. It has no known pore-clogging tendencies so acne-prone users usually tolerate it well. Those with very reactive or compromised skin should still monitor how their skin feels since any synthetic surfactant can in rare cases cause a little dryness or tightness.
The ingredient is produced entirely from petrochemical feedstocks not animal derived raw materials so products relying on it can be formulated to meet vegan and vegetarian standards. As always certification depends on the full formula and the brand’s manufacturing policies.
No published data suggest that Buteth-3 poses specific risks to people who are pregnant or breastfeeding when used topically at the low levels found in cosmetics. That said this is not medical advice and anyone expecting or nursing should discuss all personal care products with a qualified healthcare provider to be extra safe.
Buteth-3 does not increase photosensitivity and has no known interaction with sunlight so there is no special need for additional UV precautions beyond everyday sun protection habits.
Potential Side Effects/Adverse Reactions
Reactions to topical Buteth-3 differ from person to person. The effects listed below are only potential outcomes and are unlikely for the average user when the ingredient has been correctly incorporated into a finished product.
- Mild skin irritation such as transient redness or stinging
- Contact dermatitis in individuals already sensitized to polyethylene glycol type compounds
- Temporary eye irritation if the product accidentally gets into the eyes
- Slight increase in skin permeability which could enhance penetration of other actives and in rare cases lead to heightened sensitivity
If you notice any persistent discomfort itching or swelling after using a product that contains Buteth-3 discontinue use promptly and consult a healthcare professional.
Comedogenic Rating
Rating: 0
Buteth-3 is a lightweight non-ionic solvent that readily mixes with water and oil without leaving a fatty film on the skin. It is used at low concentrations and is chemically similar to other polyethylene glycol derivatives that have been tested and found non-pore-clogging. Because it is both small and water compatible it does not accumulate inside follicles or create the thick occlusive layer that usually triggers comedones.
Suitable for acne-prone or breakout-prone skin.
No data show that Buteth-3 interacts with sebum oxidation or bacterial growth so its presence in a formula should not worsen existing acne conditions.
Summary
Buteth-3’s main role in cosmetics is as a solvent that helps dissolve and evenly distribute oil-soluble and water-soluble ingredients throughout a product. Its balanced structure, with both a butyl tail and three ethylene oxide units, lets it bridge watery and oily phases so creams stay smooth, serums stay clear and actives remain stable.
While it is not a headline superstar like hyaluronic acid or niacinamide, formulators value Buteth-3 for its quiet reliability and budget-friendly cost. You will mostly find it in lightweight leave-on products, micellar waters and a handful of hair conditioners where a clean after-feel is desired.
Current safety assessments classify it as low risk when used at the small levels typical for personal care. It carries a negligible comedogenic rating, causes irritation only rarely and is considered suitable for all skin types. Still, every complexion is unique so it is smart to patch test any new product containing Buteth-3 before adding it to a regular routine.