What Is Trideceth-15 Carboxylic Acid?
Trideceth-15 Carboxylic Acid is a synthetic ingredient created by linking a tridecyl alcohol backbone to roughly 14 units of ethylene oxide, then capping the chain with a carboxylic acid group. The result is a molecule that has both water-loving and oil-loving sections, which makes it useful for mixing ingredients that would normally separate. It first appeared in the 1990s as formulators searched for milder alternatives to harsh cleansers. Production starts with fatty alcohols derived from coconut or palm kernel oil. These alcohols go through ethoxylation, where ethylene oxide units are added, followed by a controlled oxidation step that creates the terminal acid group. The finished material is a clear to slightly hazy liquid that blends easily into water-based or oil-based systems.
You will spot Trideceth-15 Carboxylic Acid in a variety of rinse-off and leave-on products. Shampoos, micellar waters, gel cleansers, moisturizing lotions, lightweight creams and occasional sheet mask essences rely on it to keep formulas stable and to lift away dirt without stripping the skin.
Trideceth-15 Carboxylic Acid’s Cosmetic Benefits/Uses
Formulators reach for this ingredient mainly for two performance roles
- Cleansing: Its surfactant nature lowers surface tension so water can spread across the skin or hair and pick up oil, makeup and debris. Because it is relatively gentle it supports mild daily cleansers that leave skin feeling fresh rather than tight.
- Emulsifying: The dual affinity structure acts like a bridge between oil and water phases, preventing separation during shelf life and ensuring a smooth even texture when the product is applied. This stability also helps active ingredients stay evenly distributed so every pump or scoop delivers the same benefits.
This ingredient is considered mild enough for most skin types including oily, combination, dry, sensitive and mature skin. It helps cleanse without a strong stripping effect so even reactive skin usually tolerates it well. People with very compromised or highly inflamed skin conditions such as active eczema or open wounds may want to avoid it until the skin barrier is repaired because any surfactant can sting on broken skin.
Trideceth-15 Carboxylic Acid is made from plant-derived fatty alcohols and synthetic processing agents so it is suitable for vegans and vegetarians. No animal-based raw materials are used in its production and it is not known to be tested on animals as a standalone compound, though final product policies vary by brand.
Current research shows no specific risks linked to topical use during pregnancy or breastfeeding. Still, this is not medical advice. Anyone who is pregnant or nursing should show the full ingredient list of any product they plan to use to their doctor just to be safe.
The ingredient does not increase sun sensitivity and has no known interactions with UV exposure. It also plays well with most other common skincare actives so formulators can pair it with acids, retinoids, antioxidants or peptides without stability issues.
Potential Side Effects/Adverse Reactions
Responses to Trideceth-15 Carboxylic Acid vary from person to person. The effects listed below are only potential outcomes and are unlikely for the average user when the ingredient is included at typical cosmetic levels.
- Mild skin irritation
- Temporary redness or stinging on very sensitive or damaged skin
- Eye irritation if the product accidentally gets into the eyes
- Contact allergy in rare cases for individuals already sensitized to ethoxylated surfactants
If you notice any burning, lasting redness or swelling after applying a product that contains Trideceth-15 Carboxylic Acid stop using it and consult a healthcare professional.
Comedogenic Rating
Rating: 1 out of 5
Trideceth-15 Carboxylic Acid is highly water soluble and built to rinse off, so it spends very little time on the skin. Its large polar structure makes it unlikely to settle inside pores which keeps clogging potential low. Typical use levels are small and usually paired with light textures that further reduce residue.
With this low score it is generally fine for acne-prone or breakout-prone skin when used in a balanced formula.
The only caveat is that if it appears in a very rich leave-on product loaded with heavy oils, the overall formula rather than this ingredient could still feel occlusive on very oily skin.
Summary
Serving as both a mild cleanser and an emulsifier, Trideceth-15 Carboxylic Acid uses its water-friendly head and oil-friendly tail to pull dirt from the skin and keep oil and water phases mixed in the bottle. This dual action helps products stay stable and feel comfortable after rinsing.
It is a quiet workhorse found in many shampoos, micellar waters and light creams. While not a buzzword for shoppers, it remains a steady favorite among formulators who need a gentle surfactant that plays nicely with actives.
Safety studies and long-term use point to a low chance of irritation or allergy, making it a generally safe choice. Still, giving any new product a quick patch test is a wise step before working it into your routine.