What Is Laureth-100?
Laureth-100 is a large molecule made by reacting lauryl alcohol, which comes from coconut or palm kernel oil, with ethylene oxide again and again until roughly 100 units are linked together. The result is a clear thick liquid that mixes easily with water and oil. Chemists began experimenting with these “laureth” materials in the mid-20th century when the personal care industry wanted gentler alternatives to harsh soaps. Because Laureth-100 is highly water loving it soon found a place in cleansers where it helps other ingredients dissolve evenly.
The manufacturing process starts with purified lauryl alcohol. This fatty alcohol is placed in a reactor with ethylene oxide gas under controlled heat and pressure. Each cycle adds one unit of ethylene oxide, and after around 100 additions the reaction is stopped, the mixture is neutralized and the finished ingredient is filtered for purity.
Today you will spot Laureth-100 in a wide range of rinse-off products such as shampoos, body washes and facial cleansers. It also shows up in makeup removers, micellar waters, sheet mask serums and some lightweight lotions where a reliable solvent and mild cleanser are needed.
Laureth-100’s Cosmetic Benefits/Uses
Here is how this ingredient improves everyday formulas:
- Solvent – Helps dissolve oils, fragrances and active ingredients so they spread uniformly in water-based products. This keeps a formula stable and prevents separation.
- Cleansing – Lifts dirt, excess oil and makeup from the skin or hair allowing them to rinse away easily. Because it is mild it supports a gentle cleansing experience that does not strip natural moisture.
Who Can Use Laureth-100
Laureth-100 is generally well received by all major skin types including oily, combination, normal and dry skin. Its mild nature makes it a good choice for sensitive skin too because it does not aggressively strip the skin’s natural barrier. People with very reactive or eczema prone skin should still keep an eye on how their skin feels, as any cleansing agent can be a bit drying if used too often or at a high level.
The ingredient is sourced from coconut or palm kernel oil and produced through a fully synthetic process, with no animal derived materials involved. For that reason products using Laureth-100 are usually suitable for vegans and vegetarians, provided the rest of the formula also meets those standards.
Current cosmetic safety data show no specific risks for women who are pregnant or breastfeeding when Laureth-100 is used as directed in rinse-off or leave-on products. This is not medical advice; anyone who is expecting or nursing should show the product to their doctor before adding it to a routine, just to be safe.
Laureth-100 is not known to make skin more sensitive to sunlight and it does not interfere with common actives such as retinoids or vitamin C. It also rinses away cleanly so it will not leave a film that could block other skincare steps.
Potential Side Effects/Adverse Reactions
Side effects from topical use of Laureth-100 can differ from person to person. The points below outline possible reactions that could occur, though most users will not experience them if the product has been formulated correctly.
- Mild skin irritation – A small number of people may notice redness stinging or tightness, especially if their skin is already compromised
- Eye irritation – Direct contact with the eyes can cause watering or burning until the product is thoroughly rinsed out
- Dryness or flaking – Overuse of a cleanser containing a high level of Laureth-100 may strip natural oils leading to temporary dryness
- Allergic contact dermatitis – Rare but possible in individuals allergic to ethoxylated surfactants, causing itching or rash
- Residual 1,4-dioxane concern – Poorly controlled manufacturing could leave trace amounts of this solvent, though reputable brands remove it to meet safety limits
If you encounter any of these issues stop using the product immediately and seek advice from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 out of 5. Laureth-100 is a large water-loving molecule that tends to stay in the water phase of a formula and rinses away easily, so it has little chance to lodge in pores and form plugs. The low rating means it is generally suitable for people who are prone to acne or breakouts. Because it is most often used in rinse-off cleansers the contact time with skin is short, which further reduces any clogging risk. One thing to note is that a formula packed with heavy oils or waxes could still be comedogenic even if it contains Laureth-100, since overall pore-clogging potential comes from the entire ingredient mix, not just one component.
Summary
Laureth-100 serves mainly as a solvent and mild cleanser. Its long chain of ethylene oxide units lets it grab onto both water and oil, so it dissolves fragrances, oils and active ingredients then helps lift dirt and makeup from skin or hair for an easy rinse. This versatility makes it a handy workhorse in shampoos, body washes, facial cleansers and some lightweight lotions, although it is not a headline ingredient consumers hunt for by name.
Most safety assessments place Laureth-100 in the low-risk category when used at the levels found in cosmetics. Irritation and sensitization are uncommon, especially in well-formulated products from reputable brands that control for residual impurities. Still, every skin is unique so it is always wise to patch test a new product before fully incorporating it into your routine.