What Is C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride?
C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride is a lab made ingredient that belongs to the family of quaternary ammonium compounds. It carries long perfluorinated carbon chains attached to a positively charged nitrogen atom, paired with chloride as the counter-ion. The perfluoro chains give it strong oil and water repelling traits while the quaternary head helps it stick to skin and hair surfaces.
The material is entirely synthetic. Chemists start with perfluoroalkylethyl mercaptans, link them to a hydroxypropyltrimethylammonium backbone through a sulfur bridge, then neutralize the mixture with hydrochloric acid to form the chloride salt. This process keeps the fluorinated part intact which is key to the ingredient’s surface active power.
Interest in this molecule grew in the early 2000s when brands looked for cleansers that could lift tough oily grime yet rinse off quickly. Its balanced structure met that need and it has since become a niche but valued option in modern personal care labs.
You will most often spot C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride in face washes, clarifying shampoos, micellar waters, long wear makeup removers, waterproof mascaras and certain anti pollution skincare formulas that target urban buildup.
C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride’s Cosmetic Benefits/Uses
This ingredient serves a single yet important role in cosmetics.
As a cleansing agent it lowers the surface tension between water and oil so dirt, sebum and long lasting makeup can be lifted away with less rubbing. Its fluorinated tail is drawn to oily residues while its charged head grabs onto water, allowing the unwanted material to be whisked off during rinsing. The result is a thorough but gentle clean that leaves skin and hair feeling fresh without a heavy film.
Who Can Use C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride
This cleansing agent suits most skin and scalp types. Oily and combination skin tend to benefit the most since the fluorinated tail locks on to excess sebum and grime. Normal skin usually tolerates it well too. People with very dry or highly reactive skin may want to watch how often they use products that feature it because its strong oil lifting action can sometimes feel too “squeaky clean” if natural moisture levels are already low.
The ingredient is fully synthetic and contains no animal sourced raw materials so it is considered suitable for both vegans and vegetarians. As always, check the finished product’s certification if cruelty free status is important since animal testing policies vary by brand and region.
No published data suggest that topical use poses a risk during pregnancy or while breastfeeding. That said this is not medical advice and anyone who is pregnant or nursing should run any skincare or haircare item past a qualified healthcare professional before adding it to their routine.
C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride does not increase photosensitivity and there are no known interactions with UV exposure. Standard daytime sun protection habits are still recommended to guard against everyday environmental damage.
Potential Side Effects/Adverse Reactions
Reactions to topical C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride vary from person to person. The points below list potential side effects only and they are unlikely to reflect most users’ experience when the ingredient is formulated correctly in a finished product.
- Mild skin dryness or tightness, especially in people who already have low oil levels
- Transient redness or tingling on very sensitive skin
- Scalp dryness or flaking if used daily in high concentration shampoos
- Eye irritation if the product accidentally gets into the eyes before rinsing
- Allergic contact dermatitis in rare cases of individual ingredient sensitivity
If any uncomfortable reaction occurs discontinue use and seek advice from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 / 5
This very low score reflects the fact that C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride is a rinse-off cleansing agent that does not leave an oily or occlusive residue. Its fluorinated tail actually repels both water and skin oils so it is unlikely to clog pores. A trace film may remain in leave-on products such as micellar waters yet even in those formats the molecule’s slippery, non-greasy nature keeps pore blockage risk minimal.
Suitable for acne-prone or breakout-prone skin.
One point to note is that formulas combining this ingredient with heavy emollients or waxes could raise overall comedogenicity, though that would be due to the other ingredients rather than the quaternary ammonium surfactant itself.
Summary
C4-18 Perfluoroalkylethyl Thiohydroxypropyltrimonium Chloride is a synthetic quaternary ammonium surfactant used to cleanse skin and hair. Its fluorinated tail grabs oily grime while the charged head binds to water so dirt, sebum and long wear makeup rinse away easily. The result is an effective yet lightweight clean that avoids the heavy feel some traditional surfactants can leave behind.
It remains a niche ingredient found mainly in performance cleansers, clarifying shampoos and waterproof makeup removers rather than everyday creams or lotions. Formulators appreciate its strong cleansing punch, although its specialized production keeps it from becoming a mainstream staple.
Safety data and real-world use show it is generally well tolerated with only mild dryness or irritation reported in sensitive users. As with any new skincare or haircare product it is wise to perform a quick patch test before regular use, just to be on the safe side.