What Is Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate?
Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate is a plant-based conditioning agent made from the fatty acids found in soybean oil and rapeseed oil. Chemically it is a quaternary ammonium salt, which means it carries a positive charge that helps it bond to the surface of hair or skin. The ingredient was developed as formulators looked for greener options to replace animal tallow derivatives that once dominated hair care. By the early 2000s suppliers had refined a process that starts by turning the vegetable oils into fatty acid methyl esters, reacting those with ethylene oxide to add a small alcohol group, then finishing with a quaternization step that converts the material into its stable methosulfate form.
This gentle process yields a biodegradable, low-odor powder or paste that disperses well in water. Because it offers strong conditioning at low use levels it is now common in rinse-off conditioners, deep masks, leave-in creams, detangling sprays, anti-frizz serums and even some skin lotions that need a light antistatic touch.
Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate’s Cosmetic Benefits/Uses
Formulators choose this ingredient for two key reasons
- Antistatic – The positive charge neutralizes the static electricity that makes hair flyaway or cling to clothing so hair looks smoother and is easier to style
- Hair conditioning – It forms a thin, lubricating film on each strand which improves softness, slip and manageability while helping to seal damaged cuticles for a healthier appearance
Who Can Use Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate
This conditioning agent is generally suitable for all skin and hair types, including oily, dry, combination and sensitive. Its plant-derived fatty acids mimic the lipids naturally found in skin and hair so most people tolerate it well. Those with very fine hair may prefer lighter formulas because heavy concentrations can weigh strands down.
The ingredient is sourced from soybean and rapeseed oils and involves no animal-derived raw materials or by-products, making it acceptable for vegans and vegetarians.
No studies have flagged special concerns for pregnant or breastfeeding women when the ingredient is used in rinse-off or leave-on hair care. Still, this is not medical advice and anyone who is pregnant or nursing should run any skincare or haircare product past a doctor just to be on the safe side.
Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate does not make skin more sensitive to sunlight so extra sun protection is not required beyond normal good habits.
Potential Side Effects/Adverse Reactions
Side effects and reactions to the topical application of Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate can vary from person to person. The following list covers potential issues only; when the ingredient is properly formulated most users will not experience them.
- Mild scalp or skin irritation in individuals with very sensitive skin
- Eye irritation if product accidentally gets into the eyes
- Build-up and limp hair when used in very high concentrations or without adequate cleansing
- Allergic contact dermatitis in the rare case of a specific allergy to soy or rapeseed derivatives
If irritation or any other negative reaction occurs discontinue use and consult a healthcare professional if symptoms persist.
Comedogenic Rating
Rating: 1 (very low)
This ingredient is water dispersible and carries a positive electrical charge that helps it sit on the surface of hair rather than soaking deep into pores. Its fatty acid chain is long enough to give slip yet the quaternary ammonium head makes it rinse away easily, so it is unlikely to block follicles or trigger comedones.
Suitable for acne-prone skin because the chance of clogging pores is minimal.
Because it is usually used in rinse-off or low-leave-on hair products, actual skin contact time is short which further reduces any pore-clogging risk.
Summary
Bis-Soyoyl/Rapeseedoyl Ethyl Hydroxyethylmonium Methosulfate works mainly as an antistatic and hair conditioning agent. Its positive charge neutralizes static electricity while the plant-derived fatty acids form a light film that smooths cuticles adds slip and boosts softness.
The ingredient has gained steady but not blockbuster popularity as brands move toward vegan and biodegradable conditioning agents. You will spot it most often in mid to high-end conditioners masks and leave-ins that promise smooth detangled hair.
Safety data show it is generally well tolerated with only rare reports of irritation or allergy. As with any new cosmetic it is wise to do a quick patch test when you try a product containing this ingredient to make sure your skin or scalp agrees with it.