Octyl Stearate

Octyl stearate is rated Caution, and there is no measurement behind that rating or behind the 5 that follows it around the consumer charts. No assay we can find has ever tested this ester — not Fulton, not the two papers that came before or after him. The two related stearate esters Fulton did put in a rabbit's ear scored 0 of 5, but those are different molecules, and an absent score is not a zero. The Caution reflects that acne clinics list it, and nothing stronger.

What it is

An emollient ester, light and spreadable, used to give a formula slip and a dry, non-greasy finish. On a modern label it reads Ethylhexyl Stearate; "Octyl Stearate" is the older name for the same material, and the word "octyl" is worth a second look, because it does not mean a straight eight-carbon chain. In the older cosmetic nomenclature "octyl" here is 2-ethylhexyl — a branched eight-carbon alcohol — so octyl stearate is the ester of 2-ethylhexanol and stearic acid, CAS 22047-49-0. The same quiet renaming sits under octyl palmitate, which is likewise ethylhexyl palmitate. The Cosmetic Ingredient Review's 2015 assessment of alkyl esters lists its cosmetic function as skin-conditioning agent (emollient). Read the name carefully, because it decides what the neighbouring rows in the rabbit-ear tables can and cannot say about it. Octyl stearate shares its acid half — stearic acid — with several esters that were tested. It does not share its alcohol half with any of them.

Why we rate it Caution

We rate it Caution at Low confidence, and the confidence is Low because there is no assay under the rating at all. The evidence tier here is an uncited list: octyl stearate appears on acne-clinic and consumer avoid-lists, and that is the whole of it. The two sources our rating file names are Face Reality's pore-clogging ingredient list and CosDNA, and both are exactly what that description says — lists, not measurements. Start with the number a reader will actually have met, because it looks like evidence and is not one. Platinum Skin Care's widely copied comedogenic chart prints "Octyl Stearate — 5" for comedogenicity and 5 for irritancy, the top of both scales. We have not found a study behind that 5. We have looked in the places a comedogenic number is supposed to come from, and it is in none of them. Fulton's 1989 rabbit-ear table is the first place to look, because nearly every circulating comedogenic number descends from it. We have his Table I transcribed by eye off a 400dpi render, all 220 rows. There is no octyl stearate row in it, and no ethylhexyl stearate row either. What is in it is two other esters of stearic acid: Octyldodecyl stearate, scored 0, and Octyldodecyl stearoyl stearate, also scored 0, both on his 0-5 scale. Those are not octyl stearate. Octyldodecyl is a twenty-carbon branched (Guerbet) alcohol; the "octyl" in octyl stearate is a branched eight-carbon one. They are the same acid on a different, much larger alcohol, and Fulton's own footnote on that section is a reminder not to read one row as another. The one thing his table does tell you directly is where the scale's top comes from: Fulton defined grade 5 as the comedones "similar to those induced by" isopropyl myristate, which he scored 5. Grade 5 is a comparison to that ester. It is not a slot that octyl stearate was ever measured into. The two other primary numeric assays do not fill the gap. Morris and Kwan, 1983 — the paper that precedes Fulton and contradicts him in print — tested eleven esters, including octyl palmitate (which they scored 2-3). Octyl stearate is not among them. Nguyen, Dang and Maibach, 2007, deemed nine of fourteen test materials positive in the rabbit ear; octyl stearate is not one of the fourteen. So the honest statement is a bounded one: we identified no comedogenicity assay of octyl stearate in any primary document we hold. The 5 on the chart is not a reading we can trace, and neither is the Caution. What we can say is that the material has never, so far as we can find, been put on a bench.

What the evidence doesn’t tell you

Everything above is an absence, and an absence has to be stated carefully. We have not proved that no one on earth ever tested octyl stearate; we have established that it is in none of the primary numeric assays we hold, and that the circulating 5 has no study attached to it that we can find. If a measurement exists in a document we have not read, this page is wrong, and it should be corrected rather than defended. The temptation this page has to resist is the reassuring one. Fulton scored the two octyldodecyl stearate esters 0, and it would be easy to let those zeros drift onto octyl stearate, since the names rhyme and the acid is the same. They cannot. The tested materials carry a twenty-carbon branched alcohol; octyl stearate carries an eight-carbon one, and we cannot assume comedogenicity is indifferent to that difference: in the tables we hold, the same acid on a different alcohol can carry a different score — Fulton put butyl stearate at 3 and octyldodecyl stearate at 0, both esters of stearic acid. A neighbouring zero is not this material's zero, in the same way that a neighbouring 5 would not be its 5. An untested ester is untested in both directions. The rabbit-ear method itself would carry the usual caution if there were a result to caution about. It applies an ingredient at roughly 10% in propylene glycol to the inner ear of three rabbits and scores follicular keratosis with a micrometer; it has been challenged as a predictor of human acnegenicity since Frank asked the question in 1982, and a 2025 review in JAAD Reviews found that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. Here that caution has nowhere to land, because there is no rabbit result for this material to begin with. The Cosmetic Ingredient Review has assessed octyl stearate and found it safe as used. That is not evidence on this page. Safety is not comedogenicity — the CIR's alkyl esters assessment is a review of irritation, sensitisation and systemic toxicity, and it says nothing about follicular plugging. An expert panel concluding a material is safe to use is a different finding from any study measuring whether it clogs a pore, and the second kind of study is the kind we could not find.

Where you’ll see it

On a label it appears as Ethylhexyl Stearate, or as the older Octyl Stearate. The CIR lists its role as an emollient; we have not audited what fraction of the market uses it or at what concentration, and we are not going to read anything off its position in an ingredient list, because position is not a dose. What is worth keeping straight is the set of names it sits near, because that is where the confusion starts. Octyldodecyl Stearate and Octyldodecyl Stearoyl Stearate are different ingredients — the ones Fulton actually scored 0 — and they are not this one. Octyl Palmitate (Ethylhexyl Palmitate) shares the same "octyl means 2-ethylhexyl" branched alcohol but a different acid, and it has its own rating. Four names a reader could flatten into one, and only the two octyldodecyl esters among them have a printed comedogenic score anywhere.

Sources

Each source says what it actually is. Several widely-cited “sources” for comedogenic ratings are republishing the same 1989 assay, and counting them as independent agreement is how a thin evidence base gets made to look thick.

1. Fulton JE. "Comedogenicity and irritancy of commonly used ingredients in skin care products." J Soc Cosmet Chem 40:321-333 (1989) The 220-row rabbit-ear table nearly every circulating comedogenic number descends from, read here off a 400dpi render of the journal scan and transcribed row by row. Method: ingredient at roughly 10% in propylene glycol, inner ear of three New Zealand albino rabbits, five days a week for two weeks, follicular keratosis scored 0-5. Cited for what it does NOT contain: there is no octyl stearate row and no ethylhexyl stearate row anywhere in it. It does contain Octyldodecyl stearate (0) and Octyldodecyl stearoyl stearate (0) — esters of a twenty-carbon branched alcohol, not of the eight-carbon one in octyl stearate — and it defines grade 5 as comedones "similar to those induced by" isopropyl myristate, which is a comparison standard, not a reading for this material.
2. Fiume MM, Heldreth BA, Bergfeld WF, et al. "Safety Assessment of Alkyl Esters as Used in Cosmetics." Int J Toxicol 34(Suppl 2):5S-69S (2015) The published final journal version of the CIR's assessment of 237 alkyl esters — not a comment-stage draft. Cited for two things, neither of which is a comedogenic score: the ingredient identity (Ethylhexyl Stearate is the ester of 2-ethylhexyl alcohol and stearic acid, CAS 22047-49-0; "Octyl Stearate" is the same material), and its cosmetic function (skin-conditioning agent/emollient). The document assesses safety — irritation, sensitisation, systemic toxicity — and concludes the ester is safe as used. It measures nothing about pores, and a safety conclusion is not evidence of noncomedogenicity.
3. Morris WE, Kwan SC. "Use of the rabbit ear model in evaluating the comedogenic potential of cosmetic ingredients." J Soc Cosmet Chem 34:215-225 (1983) An earlier rabbit-ear-canal assay on the same 0-5 scale, which contradicts Fulton in print on other materials. Three rabbits, fourteen applications, microscopic grading, materials undiluted unless the table states a dilution. Cited here only to bound the absence: it tested eleven esters, octyl palmitate among them (2-3), and octyl stearate is not one of them. Its Table III of oils is printed rotated and is lost to OCR, so anyone scraping this paper by machine loses part of it — but no version of it contains an octyl stearate row.
4. Nguyen SH, Dang TP, Maibach HI. "Comedogenicity in rabbit: some cosmetic ingredients/vehicles." Cutan Ocul Toxicol 26(4):287-292 (2007) A later rabbit external-ear-canal assay on a 0-4 scale. We have read its abstract, which lists its fourteen test materials in order and states that the first nine "were deemed positive." Cited to bound the absence: octyl stearate is not among the fourteen. This paper did not test it either.
5. Platinum Skin Care — "Comedogenic Ratings" ingredient chart One of the uncited consumer charts where a reader actually meets the number: it prints "Octyl Stearate — 5" for comedogenicity and 5 for irritancy, the top of both scales, with no source given for any row. It is not evidence, and it does not claim to be. Cited as the artefact under examination and as a measure of how loosely these charts handle the underlying papers: the same chart prints octyl palmitate at 4, a number no Fulton row supports either, and repeats several other scores this project has traced elsewhere to nothing.
6. Face Reality Skincare — pore-clogging ingredient list One of the two lists our rating file names as the basis for the Caution, and cited so a reader can see what that basis is: an acne clinic's avoid-list of ingredient names, with no comedone counts, no method, no denominator and no citation. Octyl stearate is on it. It is an assertion that the ingredient is best avoided, made by people who see acne patients — informed, but not a measurement, and we do not dress it up as one. CosDNA, the other source in our rating file, is the same kind of artefact.

Others in the same family

Esters behave similarly enough that the evidence for one is often wrongly read across to the others. These are its structural relatives, not a guess. What the evidence says about esters as a family ›

• Butyl Stearate Clogging Low
• Caprylic/Capric Triglyceride Clear Low
• Cetyl Acetate Clogging Low
• Cetyl Palmitate Clear Low
• Decyl Oleate Clogging Low
• Isocetyl Stearate Caution Low
• Isopropyl Isostearate Clogging Low
• Isopropyl Linoleate Clogging Low

Last reviewed 2026-07-12 · How we decide

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