What Is Polyquaternium-78?
Polyquaternium-78 is a synthetic polymer created by first crosslinking the gentle plant-derived surfactant decyl glucoside with 1,3-dichloro-2-propanol, then converting any leftover chloropropanol groups into positively charged quaternary ammonium sites using lauryldimethylamine. The end result is a large, water-soluble molecule that carries a permanent positive charge. This cationic nature lets it bind easily to the negatively charged surface of skin and hair, giving it staying power even after rinsing.
The wider family of polyquaterniums emerged in the 1970s as chemists looked for alternatives to traditional soaps that could cleanse without stripping and leave behind a conditioned feel. Polyquaternium-78 is one of the newer additions, engineered to combine the mild cleansing of glucosides with the conditioning of quats. Manufacturing relies on controlled, water-based reactions performed at moderate temperatures, which helps limit by-products and supports consistent quality.
You will usually spot Polyquaternium-78 in rinse-off products like shampoos, co-wash cleansers, shower gels and clarifying masks. It also appears in leave-on hair creams, frizz serums and styling sprays where its anti-static and smoothing benefits shine. Skin care formulators sometimes add it to lightweight lotions or micellar waters to give a soft finish and improve spreadability.
Polyquaternium-78’s Cosmetic Benefits/Uses
Its multitasking profile lets formulators tackle cleansing and care in one step
- Cleansing: Lifts away dirt and excess oil while being milder than sulfates so hair and skin feel clean yet not squeaky
- Hair Conditioning: Deposits a thin, positively charged film that reduces static, smooths the cuticle and boosts softness which helps detangle and enhance shine
- Emulsifying: Helps keep oil and water phases evenly mixed improving the stability and texture of creams, gels and sprays
Who Can Use Polyquaternium-78
Polyquaternium-78 is generally suitable for all skin and hair types. Its mild cleansing action keeps normal, dry, oily and combination skin feeling balanced without leaving a tight or greasy after-feel. The lightweight conditioning film also works for most hair textures, from fine to coily, without heavy buildup when used in appropriate concentrations. People with very sensitive or compromised skin may wish to introduce it slowly since any cationic polymer can occasionally cling more strongly to a weakened barrier.
The ingredient is produced from plant-derived decyl glucoside and synthetic chemicals that are not sourced from animals so it aligns with vegan and vegetarian lifestyles. As always, check the full product label for any added animal-derived fragrances or proteins that could change the ethical profile.
Current safety data shows no reproductive toxicity so pregnant or breastfeeding users can typically use products containing Polyquaternium-78. This is not medical advice and anyone expecting or nursing should clear all personal care products with a healthcare professional to be safe.
Polyquaternium-78 does not make skin more reactive to sunlight, nor does it interfere with sunscreen actives, so it is not considered photosensitising.
Potential Side Effects/Adverse Reactions
Responses to topical Polyquaternium-78 vary from person to person. The issues listed below are potential outcomes and are unlikely for most users when the ingredient is formulated and used correctly.
- Mild skin or scalp irritation such as redness or itching, typically if the overall formula is left on for extended periods or if skin is already compromised
- Allergic contact dermatitis in rare cases where an individual is sensitised to quaternary ammonium compounds
- Eye irritation if the product accidentally gets into the eyes during use, more often with shampoos and shower gels
- Product buildup on very fine hair leading to a weighed-down feel or dull appearance when not rinsed thoroughly
- Reduced performance when layered with strong anionic surfactants which may cause residue or uneven cleansing, though this is an efficacy rather than safety concern
If you notice persistent irritation, discomfort or any unexpected reaction, stop using the product and seek advice from a qualified healthcare professional.
Comedogenic Rating
Rating: 1 / 5
Polyquaternium-78 is a large, water-soluble polymer that stays mostly on the surface of skin and hair, then rinses away with water. Its film is thin and breathable so it is unlikely to block pores or trap sebum. Because it is cationic, it can bind lightly to skin, yet its size and solubility keep it from sinking into follicles where true clogging happens.
This low score means the ingredient is generally suitable for acne-prone or breakout-prone users. Only in very rich leave-on formulas used repeatedly without washing could buildup become a concern, and even then the risk is minimal.
The comedogenic scale is a guide, not an absolute guarantee, and final pore-clogging potential depends on the whole formula and personal skin chemistry.
Summary
Polyquaternium-78 delivers three main perks in cosmetics: mild cleansing, conditioning and emulsifying. Its positively charged sites grab dirt and oil so they can be rinsed away while leaving behind a smooth conditioning film that calms static and enhances softness. At the same time its polymer structure helps keep oil and water phases blended, giving products a stable, silky feel.
It is not as famous as star ingredients like hyaluronic acid or argan oil, yet formulators appreciate it for making two-in-one shampoos, co-washes and lightweight leave-ins that clean and care in a single step. You will find it mainly in niche or natural-leaning hair care lines that want a gentle surfactant with extra slip.
Current research and decades of safe use show Polyquaternium-78 has a low irritation profile, no proven systemic toxicity and a very low comedogenic score. Still, every skin is unique so perform a small patch test when trying a new product that contains it to be on the safe side.