Ingredient review
Undecylenamidopropyltrimonium Methosulfate
INCI: Undecylenamidopropyltrimonium Methosulfate
A gentle antistatic ingredient that smooths hair without heavy buildup, ideal for fine or oily hair types.
In plain English
This ingredient is a positively charged compound that sticks to the negatively charged surface of hair. It reduces flyaways and static electricity, making hair feel softer and easier to comb. It is derived from undecylenic acid, which comes from castor oil, so it is considered a semi-natural ingredient. Unlike some heavy silicones, it provides conditioning without weighing hair down.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Undecylenamidopropyltrimonium Methosulfate is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Undecylenamidopropyltrimonium Methosulfate.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A quaternary ammonium compound (a type of salt) used primarily as an antistatic and conditioning agent in hair products. It is made by reacting undecylenic acid (from castor oil) with a propyltrimonium group.
How it works
Its positive charge attracts it to the negatively charged hair shaft, forming a thin film that reduces static electricity and friction. This makes hair smoother, easier to detangle, and less prone to frizz.
Pros
Lightweight conditioning
Provides smoothness and detangling without the heavy feel of silicones or oils, making it great for fine hair.
Static control
Effectively reduces flyaways and static electricity, especially in low-humidity environments.
Cons and cautions
Limited moisture
It conditions by reducing friction, not by adding moisture, so very dry hair may still need a hydrating product.
Potential buildup
Overuse on fine hair could lead to slight residue, though it is generally less buildup-prone than other quats.
Best for
- People with fine or thin hair who want lightweight conditioning
- Anyone struggling with static or frizz in dry climates
Use caution if
- Those with very dry or damaged hair needing deep moisture (may need a richer conditioner)
- Individuals with scalp sensitivity to quaternary compounds (rare)
Usage tips
Safety summary
Considered safe for use in rinse-off and leave-on hair products at typical concentrations. Low irritation and comedogenic potential. Rare reports of scalp sensitivity in individuals with very sensitive skin.
Research notes
Clinical and safety data support its use as an effective antistatic and conditioning agent. No significant toxicity or sensitization concerns at cosmetic levels. Most evidence comes from manufacturer safety dossiers and regulatory reviews.
Common label clues
- Typical concentration
- 0.1% to 2%
- Regulatory status
- Approved for use in cosmetics in the EU, US, and other major markets. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Shampoos, Conditioners, Leave-in treatments, Hair masks
- Environmental note
- Derived from castor oil, a renewable plant source. Biodegradability data is limited, but quaternary ammonium compounds can persist in water systems; however, this one is considered relatively mild.
Good to know
- It is often used in combination with other conditioning agents to balance performance.
- The undecylenic acid precursor is derived from castor oil, making it a renewable resource.
Common questions
What is Undecylenamidopropyltrimonium Methosulfate in beauty products?
This ingredient is a positively charged compound that sticks to the negatively charged surface of hair. It reduces flyaways and static electricity, making hair feel softer and easier to comb. It is derived from undecylenic acid, which comes from castor oil, so it is considered a semi-natural ingredient. Unlike some heavy silicones, it provides conditioning without weighing hair down.
What does Undecylenamidopropyltrimonium Methosulfate do in a beauty product?
Its positive charge attracts it to the negatively charged hair shaft, forming a thin film that reduces static electricity and friction. This makes hair smoother, easier to detangle, and less prone to frizz.
Is Undecylenamidopropyltrimonium Methosulfate safe for most people?
Considered safe for use in rinse-off and leave-on hair products at typical concentrations. Low irritation and comedogenic potential. Rare reports of scalp sensitivity in individuals with very sensitive skin.
Who should be careful with Undecylenamidopropyltrimonium Methosulfate?
Those with very dry or damaged hair needing deep moisture (may need a richer conditioner) Individuals with scalp sensitivity to quaternary compounds (rare)
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.