Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 27, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer?

Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer is a hybrid ingredient created by linking small pieces of potato protein, broken down through hydrolysis, with ethyltrimonium chloride methacrylate units. The potato protein provides natural amino acids while the methacrylate part adds a positively charged, or cationic, character that helps it cling to hair. The idea of combining plant proteins with modern polymers gained traction in the late 1990s when chemists searched for ways to give hair care products a more natural origin without losing performance. Production starts with food-grade potato protein that is hydrolyzed into shorter chains, then mixed in a controlled reaction with ethyltrimonium chloride methacrylate monomers. The result is a water-soluble copolymer that carries both conditioning and strengthening properties. You will most often find this ingredient in rinse-off conditioners, leave-in sprays, hair masks and styling creams aimed at boosting softness and manageability.

Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer’s Cosmetic Benefits/Uses

In hair care formulas this ingredient serves a single core purpose: hair conditioning. Its positive charge helps it bind to the negatively charged surface of hair strands, forming a light film that smooths the cuticle, reduces static and improves slip. The added amino acids from potato protein can also help hair feel stronger and more resilient against breakage.

Who Can Use Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer

This ingredient is water soluble and lightweight so it works well for all scalp and hair types, including oily, dry, sensitive and color treated. Because it has a cationic charge and does not clog pores it is generally non problematic for sensitive or acne-prone skin that may come into contact with rinse-off products.

The copolymer is plant derived, using potato protein, and contains no animal by-products which makes it suitable for both vegans and vegetarians.

No data indicate any specific risk for women who are pregnant or breastfeeding when the ingredient is used topically in rinse-off or leave-in hair products. This is not medical advice and anyone who is pregnant or nursing should review all personal care products with their healthcare provider just to be safe.

Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer does not cause photosensitivity, so there is no additional need for sun protection beyond normal daily habits.

Potential Side Effects/Adverse Reactions

Individual responses to topical ingredients can vary. The following points list uncommon yet possible side effects; most users will experience none of these when the product has been properly formulated and used as directed.

• Mild scalp irritation such as redness or itching, usually linked to overuse or very sensitive skin

• Allergic reaction in people with a known potato or nightshade allergy resulting in itching, hives or localized swelling

• Product build-up that may leave hair feeling coated or heavy if multiple high-cationic conditioners are layered without thorough cleansing

If any of these reactions occur discontinue use and consult a healthcare professional.

Comedogenic Rating

Rating: 0/5. Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer is a water-soluble, film-forming polymer that does not leave an oily residue on skin or scalp. It rinses away easily and lacks the heavy lipids that typically clog pores, so it is considered non-comedogenic. This makes it suitable for those who are prone to acne or breakouts. Because it carries a positive charge it stays on hair rather than migrating to facial skin, further reducing any pore-clogging risk. No additional factors currently suggest a higher rating.

Summary

Ethyltrimonium Chloride Methacrylate/Hydrolyzed Potato Protein Copolymer conditions hair by using its positive charge to bond to the negatively charged hair surface, smoothing cuticles, reducing static and improving detangling. The hydrolyzed potato protein portion provides lightweight amino acids that can help hair feel stronger. While effective, it is still a niche ingredient that appears mainly in specialty conditioners, masks and leave-in sprays rather than everyday mass-market formulas.

Current research and global regulatory reviews show it to be safe for topical use with a very low risk of irritation or pore blockage. As with any new cosmetic product it is wise to perform a quick patch test before full use to ensure personal compatibility.

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