What Is Trideceth-18?
Trideceth-18 is a synthetic ingredient made by attaching about eighteen units of ethylene oxide to tridecyl alcohol, creating a polyethylene glycol ether that mixes well with both oil and water. It comes from fatty alcohols that are usually derived from coconut or palm oil, then processed in the lab through a step called ethoxylation. First introduced to cosmetics in the late twentieth century, it offered formulators a gentle way to blend oily and watery ingredients without leaving a heavy feel. Today you will spot Trideceth-18 in many rinse off and leave on products like facial cleansers, shampoos, micellar waters, makeup removers, lotions, lightweight creams, masks and even some hair conditioners.
Trideceth-18’s Cosmetic Benefits/Uses
This ingredient earns its place on the label by making formulas work better and feel nicer on the skin or hair.
- Cleansing: Its ability to grab oil and dirt while staying water friendly helps products rinse away impurities without harsh scrubbing, leaving skin or hair feeling fresh and soft.
- Emulsifying: It keeps oil based and water based ingredients evenly mixed so the product stays smooth, stable and pleasant to apply from the first use to the last.
Who Can Use Trideceth-18
Because it is mild and not oily or heavy, Trideceth-18 suits most skin types, including oily, combination, normal and even some sensitive skins that react to harsher surfactants. Extremely reactive or allergy-prone skin may still want to proceed with caution only because any synthetic surfactant can be a potential irritant when used at high levels.
The ingredient is usually sourced from plant-based fatty alcohols such as coconut or palm oil, and no animal by-products are part of its standard production, so it is generally considered acceptable for vegans and vegetarians. As always, ethical shoppers may wish to confirm that the finished product, not just the raw material, is cruelty free.
No studies have shown Trideceth-18 to pose a special risk during pregnancy or while breastfeeding. Topical absorption is minimal, but this is not medical advice and anyone pregnant or nursing should ask a doctor before adding new skincare just to be safe.
Trideceth-18 does not make skin more sensitive to sunlight, and there are no known ingredient conflicts that would rule out its daytime use. People with a known polyethylene glycol allergy should avoid it, but otherwise it can be used morning or night in face, body and hair formulas without extra precautions.
Potential Side Effects/Adverse Reactions
Reactions to topical Trideceth-18 differ from person to person. The points below list potential side effects yet most users will not experience them when the ingredient is formulated and used correctly.
- Skin irritation: Redness, stinging or dryness may occur in those with very sensitive or compromised skin barriers
- Allergic contact dermatitis: Rare cases of itching, rash or swelling have been reported in individuals allergic to polyethylene glycol compounds
- Eye irritation: High concentrations can cause temporary burning or watering if a product accidentally gets into the eyes
- Contaminant concerns: If poorly purified, trace amounts of 1,4-dioxane could be present though reputable manufacturers remove this substance to safe levels
If you notice any discomfort or reaction while using a product that contains Trideceth-18 stop using it immediately and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 0–1 (non to very low). Trideceth-18 is a lightweight water-soluble surfactant that rinses off easily and does not leave an oily film on the skin. Because it does not linger in pores or add occlusive residue, it earns a score at the bottom of the scale.
That makes it generally suitable for people who are prone to acne or breakouts.
As with most PEG ethers, any breakout that does occur is more likely linked to the overall formula or to individual sensitivity rather than to Trideceth-18 itself.
Summary
Trideceth-18 works as a cleanser and an emulsifier, meaning it helps lift away oil and dirt while keeping water and oil ingredients blended so a product stays smooth and stable. It does this thanks to its dual-loving structure that grabs both water and oil, then washes clean without heaviness.
You will find it in a fair number of face washes, micellar waters, lotions and hair cleansers, though it is not a headline ingredient that brands highlight the way they do with actives like vitamin C or retinol.
Current safety reviews place Trideceth-18 in the low-risk category for irritation or toxicity when used at normal cosmetic levels. Still, everyone’s skin is unique so it is wise to do a quick patch test whenever you try a new product that contains it.