Ingredient review
Butoxynol-19 Carboxylic Acid
INCI: Butoxynol-19 Carboxylic Acid
An effective synthetic cleanser that can be drying for sensitive skin, but is generally safe in well-formulated products.
In plain English
Butoxynol-19 Carboxylic Acid is a man-made ingredient that helps cleansers foam up and lift away dirt and oil from your skin. It belongs to a family of surfactants (soap-like compounds) that work by breaking the surface tension between water and oil, so grime rinses away easily. However, because it can strip some of your skin's natural moisture, it may feel drying if you have a sensitive or dry skin type.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Butoxynol-19 Carboxylic Acid can be useful, but watch for some irritation potential.
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 Butoxynol-19 Carboxylic Acid.
- 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
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
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 synthetic carboxylic acid derivative of butoxynol, used primarily as a surfactant in cosmetic cleansing products.
How it works
It reduces the surface tension between water and oil, allowing water to mix with and wash away sebum, dirt, and makeup. Its carboxylic acid group gives it mild anionic (negatively charged) properties that help stabilize foam and improve cleansing efficiency.
Pros
Strong cleanser
Effectively removes excess oil, dirt, and makeup, making it great for oily skin types.
Foam booster
Helps create a rich, satisfying lather that many people enjoy in their cleansing routine.
Cons and cautions
Potential dryness
Can strip the skin's natural moisture barrier, leading to tightness or irritation, especially for dry or sensitive skin.
Synthetic origin
Not derived from natural sources, which may be a concern for those seeking plant-based or eco-friendly ingredients.
Best for
- People with oily or combination skin who want a deep cleanse
- Those who prefer foaming cleansers
Use caution if
- Individuals with very dry, sensitive, or eczema-prone skin
- Anyone looking for a completely natural or biodegradable cleanser
Usage tips
Safety summary
Generally recognized as safe for cosmetic use in rinse-off products at typical concentrations. However, it can be drying or irritating for sensitive skin, so patch testing is recommended for new users.
Research notes
Limited peer-reviewed studies specifically on Butoxynol-19 Carboxylic Acid, but related carboxylic acid surfactants are well-documented as effective cleansers with moderate irritation potential. Safety assessments by industry panels support its use in cosmetics.
Common label clues
- Typical concentration
- Typically 1–10% in rinse-off formulas
- Regulatory status
- Approved for use in cosmetics in the US (FDA) and EU (CosIng) at concentrations up to 10% in rinse-off products.
- Common uses
- Facial cleansers, Body washes, Shampoos
- Environmental note
- As a synthetic surfactant, it may have moderate biodegradability; look for formulations that emphasize eco-friendly cleansing if this is a concern.
Good to know
- This ingredient is often found in combination with milder surfactants to reduce irritation.
- It is not typically used in leave-on products like lotions or serums.
Common questions
What is Butoxynol-19 Carboxylic Acid in beauty products?
Butoxynol-19 Carboxylic Acid is a man-made ingredient that helps cleansers foam up and lift away dirt and oil from your skin. It belongs to a family of surfactants (soap-like compounds) that work by breaking the surface tension between water and oil, so grime rinses away easily. However, because it can strip some of your skin's natural moisture, it may feel drying if you have a sensitive or dry skin type.
What does Butoxynol-19 Carboxylic Acid do in a beauty product?
It reduces the surface tension between water and oil, allowing water to mix with and wash away sebum, dirt, and makeup. Its carboxylic acid group gives it mild anionic (negatively charged) properties that help stabilize foam and improve cleansing efficiency.
Is Butoxynol-19 Carboxylic Acid safe for most people?
Generally recognized as safe for cosmetic use in rinse-off products at typical concentrations. However, it can be drying or irritating for sensitive skin, so patch testing is recommended for new users.
Who should be careful with Butoxynol-19 Carboxylic Acid?
Individuals with very dry, sensitive, or eczema-prone skin Anyone looking for a completely natural or biodegradable cleanser
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.