Porecelain

Flawless skin starts with the fine print.

Stearyl Alcohol

Stearyl alcohol is one of the few ingredients on this site named in three separate rabbit-ear documents rather than one — Fulton's 1989 table prints 2 on a 0 to 5 scale, a score his own key calls borderline, and the two other reports that mention it print no number at all: one records a negative at second hand, the other simply leaves it out of the materials it deemed positive.

Caution Low confidence Legacy score 2 on a 0-5 scale · Fulton 1989 · low reliability

Fulton 1989 scored 2 of 5 — borderline under his own key, and the only reading we hold.

What it is

An eighteen-carbon fatty alcohol, and the word "alcohol" is where the worry comes from. Ethanol is a two-carbon liquid that evaporates off the skin; this is a solid. The Cosmetic Ingredient Review's 1985 final report describes it as white flakes or granules with a faint fatty odour, a molecular weight of 270.5 for the pure compound, and a melting point the report's table gives in the range of 51 to 60 degrees Celsius. It is also worth knowing that the label name does not denote a single molecule. The same report states plainly that "the materials of commerce are mixtures of fatty alcohols" and that the term stearyl alcohol refers to that mixture throughout: predominantly n-octadecanol at a 90 percent minimum assay, with varying amounts of other fatty alcohols (chiefly n-hexadecanol, n-tetradecanol and n-dodecanol), "along with unspecified uneven and branched-chain alcohols." CAS number 112-92-5. Formulators use it as an emollient, an auxiliary emulsifier, a thickener and an emulsion stabiliser — the CIR quotes a Society of Cosmetic Chemists communication describing it as a bodying and pearlizing agent that produces a semiocclusive film, and notes it is used as an opacifier in shampoos and bubble baths. It is closely related to, but not the same material as, cetyl alcohol (sixteen carbons) and cetearyl alcohol (a mixture of the two).

Why we rate it Caution

We rate it Caution, at Low confidence. The only number anyone printed for this ingredient sits in the band its own author called borderline, and everything below happened on a rabbit's ear. The number people quote is a 2, and unlike most numbers on this site it belongs to this ingredient. James Fulton's 1989 rabbit-ear survey in the Journal of the Society of Cosmetic Chemists, Table I prints "Stearyl alcohol" and scores it 2 for comedogenicity on a 0 to 5 scale. We render the table at 400dpi and read all 220 rows by eye, because OCR drops the numeric columns. The row says what it appears to say. That is worth stating plainly, because on many pages of this site it does not: coconut oil has no row, lanolin has no row, rosehip oil has no row at all. Stearyl alcohol does. The method behind it: the ingredient diluted to roughly 10 percent in propylene glycol, 1 ml applied to the inner ear of New Zealand albino rabbits, three rabbits per assay, five days a week for two weeks, follicular keratosis then measured with a micrometer. And Fulton's own key to his own scale, which almost nobody quotes beside the number: "a minimal grade of 0 to 1 is not considered significant. Grade 2 to 3 is borderline. However, a grade of 4 to 5 is uniformally reproduceable and considered positive." By the standard of the man who produced it, a 2 is borderline. It is below his threshold for a positive result and above the band he called insignificant. It is not a finding of comedogenicity, and it is not a clean bill of health either. What makes this page unusual is that the 2 is not the only document. Two others name this exact material, and neither of them prints a number. The first is older than Fulton. The Cosmetic Ingredient Review's 1985 final report on stearyl alcohol, oleyl alcohol and octyl dodecanol carries a section headed "Comedogenicity", and it reads in full: "Stearyl Alcohol was not comedogenic when applied to the ear canal of 2 rabbits 5 days per week, for 2 weeks." The reference given for that sentence is Kligman AM and Mills OH Jr, "Acne cosmetica", Arch Dermatol 106(6):843-850 (1972) — the paper that started the whole rabbit-ear literature. The report's own summary states that "Stearyl Alcohol produced no evidence of contact sensitization or comedogenicity," and its discussion repeats that "a rabbit ear comedogenicity test on Stearyl Alcohol was negative." The second is more recent. Nguyen, Dang and Maibach's 2007 report in Cutaneous and Ocular Toxicology lists fourteen materials it examined in the rabbit external ear canal — isopropyl palmitate, isopropyl myristate, butyl stearate, isopropyl isostearate, decyl oleate, isostearyl neopentanoate, isocetyl stearate, myristyl myristate, cocoa butter, cetyl alcohol, paraffin, stearyl alcohol, sodium lauryl sulfate and petrolatum — and then states: "The first nine were deemed positive." Stearyl alcohol is twelfth on that list. It was not among the nine. No per-material score is printed in anything we have read of that paper, so what it gives us is a classification and not a measurement. So the record is three documents and one printed number, and the number is the only one of the three scored on a scale we can read. It landed in Fulton's borderline band: not a positive, and not the clean zero the consumer lists print. The other two reach a negative verdict without a figure — the CIR's is a single sentence reported at second hand from a 1972 paper we have not obtained, and Nguyen's is an absence from a list of positives — and an unnumbered verdict does not resolve a borderline number. Caution is our word for a reading that has not been resolved. Beyond these three, Fulton's own 1984 survey has no stearyl alcohol row, and neither does Morris and Kwan 1983.

What the evidence doesn’t tell you

Three rabbit-ear documents are still three rabbit-ear documents. This is the same assay we discount everywhere else on this site, and the reasons do not stop applying because a number is low. Draelos and DiNardo argued in 2006 that rabbit-ear results do not reliably predict comedogenicity in human skin; the 2025 JAAD Reviews survey of the field found that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated claim. Those are the grounds on which we refuse to trust the 4s. They apply identically to a 2 and to two unnumbered negatives. We identified no study that counted comedones on human skin after applying stearyl alcohol. We have read the table of exactly one of the three documents, and that matters more than the count of three suggests. For the CIR's negative, we have the report's own sentence and nothing behind it. It gives no concentration, no vehicle, no scale, no score and no grading method — only two rabbits, ten applications, and the word "not". We have not obtained the full text of Kligman and Mills 1972, so we cannot confirm from the paper itself which materials its tables list or how stearyl alcohol was graded there. We are reporting what the CIR reports, and saying so. Kligman later published a critical reappraisal of that 1972 model, on the grounds that it produced positives for bland greases; he did not withdraw the paper, and we are not treating the reappraisal as either a cancellation of this result or a reason to lean on it. For the 2007 report, we have the abstract and the opening paragraph of its book-chapter version and no more. It runs four pages. Its own first paragraph says it "reports our finding on the activity of certain raw materials previously investigated," which leaves open how much of it is new bench work and how much is a re-examination of materials the earlier assays had already covered — we cannot tell from the abstract, and we are not going to guess. It prints no per-ingredient scores in anything we have read, so "not among the nine deemed positive" is the most that sentence will carry. It is also not a quiet corroboration of the earlier work: the same list deems isocetyl stearate positive, where Morris and Kwan 1983 scored that material 0-1 on a 0 to 5 scale. Papers in this corpus contradict each other, and a paper agreeing with us on one row is not thereby reliable. The material identity is looser than the label suggests. Every one of these documents tested something called stearyl alcohol, and the CIR's own definition of that name is a mixture that is at least 90 percent n-octadecanol and otherwise unspecified, including "unspecified uneven and branched-chain alcohols." None of the three reports discloses a supplier or a certificate of analysis. Whether they tested the same mixture is not recoverable. One argument we will not offer, because we made it ourselves and it was wrong. The common defence of fatty alcohols is that the molecule is simply too large to enter a follicle. On our own cetearyl alcohol page we wrote that these ingredients sat beyond the 200 to 300 molecular-weight band Fulton discussed as the zone of maximum follicular penetration. Stearyl alcohol's molecular weight, from the CIR's own table, is 270.5. It is inside that band. Whatever the band is worth — and it is an observation about one man's ingredient set, not a law — it is not an argument in this ingredient's favour, and we found no study measuring follicular penetration of stearyl alcohol in either direction. A printed contrast we can report but cannot explain: in the same section of the same Fulton table, oleyl alcohol — the eighteen-carbon fatty alcohol with one double bond, assessed alongside stearyl alcohol in that same 1985 CIR report — scores 4, inside the band Fulton called positive. Stearyl scores 2. Fulton offers no explanation for the difference anywhere in his prose, and we have found no study testing whether the unsaturation is responsible. We print both numbers because they are both printed. We are not turning the gap between them into a mechanism. Finally, the ingredient's best-documented human liability is a different question entirely. The CIR's 1985 report collates screening patch-test data giving 19 positive reactions in 3,740 subjects for stearyl alcohol — about 0.51 percent in pooled screening, before accounting for test concentration, vehicle or population. That is contact allergy, not comedones. The two questions have different answers, and where an ingredient lands on this site says nothing about whether it is the reason a particular person cannot use most of the creams in a pharmacy.

Where you’ll see it

Creams and lotions rather than gels and serums, plus shampoos and bubble baths, where the CIR notes it is used as an opacifier. In the CIR's 1981 use data it was reported in 425 cosmetic formulations at concentrations ranging from less than 0.1 percent to 50 percent, with very few products at the highest ranges. That data is forty-five years old and the report itself cautions that its concentration figures may overstate actual use by two- to ten-fold, so we offer it as a record of what was reported then, not as a description of a shelf today. Nearby on a label you will often meet cetyl alcohol and cetearyl alcohol; they are related materials with their own separate numbers, and the evidence on this page does not transfer to them.

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 only document we have read that puts a number on this ingredient. Design — ingredient at roughly 10% in propylene glycol, 1 ml applied to the inner ear of New Zealand albino rabbits, three rabbits per assay, five days a week for two weeks, follicular keratosis measured with a micrometer. Scale 0 to 5. "Stearyl alcohol" appears among the alcohol rows of Table I, scored 2 for comedogenicity. Our transcription records section headings for two blocks of that paper only, and this is not one of them, so we give the row rather than a heading we cannot produce. The paper also prints an irritancy column, which we do not quote, because our verbatim transcription of Table I carries the comedogenicity column only. What it cannot support — Fulton calls his own survey "not at all definitive but simply designed to stimulate research", warns that the rabbit ear is so sensitive that "not everything that irritates this model will also irritate human skin", and defines his grades so that 2 is "borderline" rather than positive. One animal assay, one laboratory, at a concentration and under a regime no product reproduces.
  2. Cosmetic Ingredient Review. "Final Report on the Safety Assessment of Stearyl Alcohol, Oleyl Alcohol, and Octyl Dodecanol." J Am Coll Toxicol 4(5):1-29 (1985) A final report, not a tentative or comment-stage draft — the document read for this page is the published journal version, headed "Final Report on the Safety Assessment of Stearyl Alcohol, Oleyl Alcohol, and Octyl Dodecanol", Journal of the American College of Toxicology volume 4, number 5, 1985. Industry-funded, independently panelled toxicological safety review. Unlike the CIR's report on the cetyl and cetearyl alcohols, this one does address comedogenicity: it carries a section under that heading, one sentence long, reporting a negative rabbit-ear-canal result in 2 rabbits and attributing it to Kligman & Mills 1972. It states no concentration, vehicle, scale or score. The source of all chemistry, use and patch-test figures on this page — the 270.5 molecular weight, the 51 to 60 degree melting range, the "mixtures of fatty alcohols" definition and the 90 percent minimum assay, the 1981 use survey (425 formulations, less than 0.1% to 50%, with the report's own warning of a possible 2- to 10-fold overestimate), and the 19-in-3,740 patch-test rate. Its overall conclusion is a safety conclusion, and safety is not noncomedogenicity.
  3. Kligman AM, Mills OH Jr. "Acne cosmetica." Arch Dermatol 106(6):843-850 (1972) The paper the rabbit-ear literature descends from, and the source the CIR gives for its negative comedogenicity finding on stearyl alcohol. Rabbit external ear canal, scale 0 to 3 — a DIFFERENT scale from Fulton's 0 to 5, so its results cannot be read across. Cited here at one remove and labelled as such: we have not obtained the full text, and we cannot confirm from its abstract which materials its tables list or how stearyl alcohol was graded. Kligman later published a critical reappraisal of this model on the grounds that it produced positives for bland greases, and updated the assay; the paper was not withdrawn. Read as what it is — a 1972 animal screen, reported to us secondhand by a 1985 safety review.
  4. Nguyen SH, Dang TP, Maibach HI. "Comedogenicity in rabbit: some cosmetic ingredients/vehicles." Cutan Ocul Toxicol 26(4):287-292 (2007); also published as chapter 58, pp. 601-604, in Handbook of Cosmetic Science and Technology (CRC Press, 2009) A four-page rabbit-external-ear-canal report on a 0 to 4 scale. We have read its abstract and the opening paragraph of the book-chapter version, and no more: no table, no per-ingredient score, no n, no concentration, no vehicle. Its abstract lists fourteen materials and says "the first nine were deemed positive"; stearyl alcohol is twelfth. That is the entire finding we draw from it, and it is a verdict rather than a number. Its chapter version opens by saying it "reports our finding on the activity of certain raw materials previously investigated", which leaves the balance of new bench work and re-examination unclear from what we have read. Not offered as clean corroboration — its nine positives include isocetyl stearate, which Morris and Kwan scored 0-1 on a 0 to 5 scale in 1983.
  5. Draelos ZD, DiNardo JC. "A re-evaluation of the comedogenicity concept." J Am Acad Dermatol 54(3):507-512 (2006) A "Current Issues and Opinion" piece testing finished products on a small number of upper-back panels — not a same-substance rabbit-versus-human validation study. It argues that rabbit-ear results do not reliably predict comedogenicity in human skin and that testing an isolated ingredient says little about a finished formula. Cited against our own rating as much as for it: it is why the confidence here stays Low even with three documents in the record.
  6. "Comedogenicity in cosmeceuticals: a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) A recent peer-reviewed narrative review covering the literature from 1972 to 2025. Finds that no standardised comedogenicity test exists and that the "non-comedogenic" claim is unregulated. A synthesis, not new data, and not independent of the legacy assays in the sense of testing anything — but independent of the consumer lists that republish them.
  7. Acne.org, "What Is Comedogenicity, and What Ingredients Are Comedogenic?" A commercial acne-products site that also publishes an ingredient list, cited to characterise the secondary literature accurately rather than lazily. It is not a bare republication of one assay — it states a rule, requiring two rabbit-ear assays or one human-method test to reach its "avoid" list and one assay for "consider avoiding", and it cites primary papers. It is still a list compiled from other people's animal work, with no measurement of its own. We did not attempt to fetch the page during this write-up and make no claim about which list, if either, carries stearyl alcohol.

Others in the same family

Fatty alcohols 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 fatty alcohols as a family ›

Last reviewed 2026-08-20 · How we decide

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