Butyl Stearate
Butyl stearate is rated 3 to 4 on our list, a range whose top puts it in the high band, and the number is traced: Fulton 1989 graded it 3.
Like every rating here, it is for the raw ingredient tested alone, and a label does not print how much of it a product holds.
Is butyl stearate comedogenic?
Butyl Stearate is rated 3–4 on the comedogenic scale: our list gives it a range from 3 to 4, and the band follows the 4 at the top. The rabbit-ear studies we have read give it less: Fulton 1989 gave it 3. Our list's 4 is above all of them.
A synthetic compound used to decrease the thickness of liquids and condition skin.
- Comedogenic rating
- 3–4 out of 5 (a range on our list)
- Band
- High: Clear plugging in the rabbit-ear test. The first band to check in a leave-on product.
- Where the number comes from
- Traced to Fulton 1989. The section on who rated it prints each grade.
- Composition
- Ester / Fatty Acids & Derivatives
- Also written as
- No common variants recorded
What a 3–4 means in practice
A 4 or 5 is the top of the scale. In the rabbit-ear test, Fulton 1989 counted 4 to 5 as a clear positive: the ingredient plugged the follicles, and did so repeatably. A person's skin reacts less readily than a rabbit's ear, and a product holds far less of the ingredient than the test did, so treat this band as the first thing to check in anything that stays on your skin. It does not prove the ingredient will cause a breakout. A rinse-off product is on the skin for seconds.
Two things change what this number is worth. Ingredients are listed in descending order of concentration, so butyl stearate near the top of a label matters far more than butyl stearate at the bottom. And the rating describes the raw ingredient on its own. A 2006 review in the Journal of the American Academy of Dermatology found that a rating for a single ingredient does not reliably predict how a finished formula behaves on human skin. The full story of the scale is here.
Who rated it
Our list is one band above the research. Our list gives butyl stearate 3–4. Fulton 1989 gave it 3. We report the list as it stands and show the papers beside it. Where the list and the research disagree.
Our list gives butyl stearate 3–4. These are the figures the published rabbit-ear studies we have read give it, as printed in each paper's table.
| Paper | Grade | Tested as |
|---|---|---|
| Fulton 1989 | Grade 3 | Tested as Butyl stearate |
Ahn and colleagues 1985 reports severe comedogenicity in the rabbit ear canal, in an abstract that gives no 0 to 5 grade.
Our list's top figure, 4, is higher than anything in these papers.
Fungal acne
Butyl Stearate matches rule 2, ester of a C12 to C24 fatty acid , on the fungal acne checker. An ester of stearic acid, C18. The rule comes from lab studies of what Malassezia yeast can feed on, and it is not a verdict on any product.
Common questions
- Is butyl stearate comedogenic?
- Butyl Stearate is rated 3–4 on the comedogenic scale: our list gives it a range from 3 to 4, and the band follows the 4 at the top. The rabbit-ear studies we have read give it less: Fulton 1989 gave it 3. Our list's 4 is above all of them.
- Is butyl stearate non comedogenic?
- No. Butyl Stearate is rated 3–4 on the comedogenic scale, which is the high band. That is the number on our list; the papers we read grade it lower (see Who rated it).
- What is butyl stearate's comedogenic rating?
- 3–4 out of 5 on our list. It is classed as Ester / Fatty Acids & Derivatives. The rabbit-ear studies we have read give it less: Fulton 1989 gave it 3. Our list's 4 is above all of them.
Sources we checked this rating against
- Kligman AM, Kwong T. “An improved rabbit ear model for assessing comedogenic substances.” British Journal of Dermatology, June 1979;100(6):699–702. (opens in a new tab) The rabbit-ear assay behind published 0 to 5 comedogenicity grades.
- Fulton JE Jr. “Comedogenicity and irritancy of commonly used ingredients in skin care products.” Journal of the Society of Cosmetic Chemists, November/December 1989;40(6):321–333. (opens in a new tab) Rabbit ear. Each ingredient at 10 percent in propylene glycol unless stated, applied five days a week for two weeks, and graded 0 to 5 from the width of the follicles, measured by micrometer and under the microscope. The paper counts 0 to 1 as not significant, 2 to 3 as borderline and 4 to 5 as positive. Some grades depended on the supplier of the raw material, and some oils were also tested refined.
- Ahn HY, Myung KB, Hahm JH, Kook HI. “An experimental study on comedogenicity of several external contactants.” Korean Journal of Dermatology, October 1985;23(5):620–629. (opens in a new tab) Rabbit ear canal; in the abstract’s words, the materials were applied to one ear canal of rabbits "for 6 weekdays for 2 weeks". Read at abstract level: the full text is not online. The abstract sorts ingredients into none, mild, moderate and severe with no 0 to 5 grade, and lists propylene glycol under both none and moderate. Kligman 1996 says that putting test materials inside the ear canal gave false positives in his own 1972 study, because loose horny material collects in the follicles there.
- Draelos ZD, DiNardo JC. “A re-evaluation of the comedogenicity concept.” Journal of the American Academy of Dermatology, March 2006;54(3):507–512. doi:10.1016/j.jaad.2005.11.1058 (opens in a new tab) Tested finished products on the backs of six people and concluded that “Finished products using comedogenic ingredients are not necessarily comedogenic.”