Ingredient review
Ethyl Butylacetylaminopropionate
INCI: Ethyl Butylacetylaminopropionate
A well-studied synthetic insect repellent that is gentle on skin and widely recommended as an alternative to DEET.
In plain English
Ethyl Butylacetylaminopropionate (often called IR3535) is a man-made ingredient that keeps bugs away. It works by confusing the insects' sense of smell so they don't land on your skin. It's commonly used in lotions and sprays for outdoor protection and is considered very safe for most people, including children.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is relatively strong for its common cosmetic role.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- strong
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Ethyl Butylacetylaminopropionate 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 Ethyl Butylacetylaminopropionate.
- 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
strongThere is a stronger practical or research basis for the ingredient role described here.
What it is
A synthetic compound derived from the amino acid beta-alanine, developed in the 1970s and approved for use as an insect repellent by major health agencies worldwide.
How it works
It interferes with the olfactory receptors of mosquitoes, ticks, and other biting insects, making human skin less detectable and less attractive to them.
Pros
Gentle on skin
IR3535 has a very low irritation and sensitization rate, making it a good choice for people with sensitive skin or those who react to harsher repellents like DEET.
Proven effectiveness
Extensively tested and recommended by the CDC and WHO for protection against mosquitoes that may carry diseases like West Nile virus or Zika.
Cons and cautions
Shorter protection time
Compared to high-concentration DEET, IR3535 may need to be reapplied more frequently, especially in heavy mosquito activity or after swimming or sweating.
Not a one-size-fits-all
While effective against many insects, it may not repel all species equally well, so check local recommendations for your area.
Best for
- People spending time outdoors in buggy areas
- Those with sensitive skin who react to DEET
- Families looking for a DEET-free repellent
Use caution if
- Infants under 2 months old (check product label)
- Anyone with a known allergy to the ingredient
Usage tips
Safety summary
Extensive safety testing shows Ethyl Butylacetylaminopropionate is safe for topical use at recommended concentrations. It has very low skin irritation and sensitization potential and is not known to cause long-term health issues.
Research notes
Multiple peer-reviewed studies and regulatory reviews confirm its efficacy as an insect repellent. It is listed as a recommended active ingredient by the CDC for preventing mosquito-borne diseases.
Common label clues
- Typical concentration
- 10% to 20% for effective repellency
- Regulatory status
- Approved as an insect repellent by the U.S. EPA, the European Chemicals Agency, and the World Health Organization. It is classified as a biopesticide due to its amino-acid origin.
- Common uses
- Insect repellent lotions, Sprays, Wipes, Outdoor skincare
- Environmental note
- IR3535 is biodegradable and has low toxicity to aquatic life, making it a more environmentally friendly option compared to some other synthetic repellents.
Good to know
- IR3535 is approved by the EPA and is considered safe for use on children and adults.
- It has a very low toxicity profile and is biodegradable.
Common questions
What is Ethyl Butylacetylaminopropionate in beauty products?
Ethyl Butylacetylaminopropionate (often called IR3535) is a man-made ingredient that keeps bugs away. It works by confusing the insects' sense of smell so they don't land on your skin. It's commonly used in lotions and sprays for outdoor protection and is considered very safe for most people, including children.
What does Ethyl Butylacetylaminopropionate do in a beauty product?
It interferes with the olfactory receptors of mosquitoes, ticks, and other biting insects, making human skin less detectable and less attractive to them.
Is Ethyl Butylacetylaminopropionate safe for most people?
Extensive safety testing shows Ethyl Butylacetylaminopropionate is safe for topical use at recommended concentrations. It has very low skin irritation and sensitization potential and is not known to cause long-term health issues.
Who should be careful with Ethyl Butylacetylaminopropionate?
Infants under 2 months old (check product label) Anyone with a known allergy to the ingredient
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.