Porecelain

Flawless skin starts with the fine print.

Fatty alcohols

Every comedogenic number these five materials carry was produced in one laboratory. Fulton scored all five, and two of them twice. The two documents we identified from other laboratories both landed on materials he had already placed in his borderline band — one sentence about stearyl alcohol, reported at second hand, and cetyl and stearyl alcohol's absence from a list of positives — and neither gives a per-material figure in what we have read of it. Of the two he placed in his positive band, isocetyl alcohol at 4 of 5 and oleyl alcohol at 4 of 5, we identified no reading by anyone else.

5 rated 2 Clogging 3 Caution 0 Clear 0 never assayed

What they are

Long-chain alcohols. The hydroxyl group on the end is the only thing they share with the alcohol people are worried about when they see the word on a label — ethanol is a two-carbon liquid that evaporates off the skin, and these are sixteen and eighteen carbons long and, with one exception, waxy solids that have to be melted into a formula. Formulators use them to thicken an emulsion and hold it together. The five we rate are not interchangeable, and two of them need their identity stated before any number is quoted. CETEARYL ALCOHOL is not a single compound at all — the name covers a mixture of stearyl and cetyl alcohols in proportions set by the manufacturer rather than by the name, so two products declaring it need not hold the same material. OLEYL ALCOHOL is the one that is not a waxy solid — it is eighteen carbons with a double bond in the middle, and it is a liquid. ISOCETYL ALCOHOL has the same C16 formula as cetyl alcohol arranged differently, with a branched chain rather than a straight one. Cetyl and stearyl alcohol are the straight, saturated C16 and C18. Now the part where Fulton's table and our family are different sets, which is a mistake we have made on a hub before. The rows that run with these five in the printed table are a list of things called alcohols, not a list of fats. Running with them are MYRISTYL ALCOHOL at 2 of 5; CETEARETH-20 at 2 of 5 and a row Fulton prints as "Cetearyl alcohol + ceteareth 20" at 4 of 5; and SD ALCOHOL 40 at 0 of 5 and ISOPROPYL ALCOHOL at 0 of 5, the volatile solvent alcohols, which are not fatty alcohols at all. We rate none of those five. None of them is in any family on this site and none has an entry in our ratings file, so none will appear in the table on this page — which is worth saying plainly, because a reader who assumes the rows and the family are the same set will come away with two numbers we do not stand behind. In the order our transcription records, the two rows that are actually the drying kind of alcohol are the two lowest of them. That is a remark about how the source is organised. It is not a finding about dryness, which is a different endpoint that this assay did not measure. One precision about that last point, because it is the kind we go after other people for. Our 400dpi transcription records section headings for only two blocks of that paper, and no heading over any of these rows. So what we hold is the order the rows run in, and not what, if anything, is printed above them. Where a page of ours has named a heading here, it is not resting on this transcription, and we are not going to repeat it.

What the evidence actually says

Start with the key, because it belongs to the whole family, and a bare digit on a chart does not carry it. Fulton wrote, of his own scale: "As reported in our previous studies, 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." Read against that key, his five readings are not one series of digits. Cetyl alcohol 2 of 5, cetearyl alcohol 2 of 5 and stearyl alcohol 2 of 5 are borderline by the standard of the man who produced them — not a finding of comedogenicity, and not a clean result either. Isocetyl alcohol 4 of 5 and oleyl alcohol 4 of 5 are positive by that same standard. Three of one thing and two of another, and the lists reprint all five as bare numbers on a chart. Fulton read two of them a second time, in his earlier 1984 survey. Oleyl alcohol scored 4 of 5 there too. Cetyl alcohol scored 3 of 5, one grade higher than the 1989 row, and the two papers do not share a key: 1984 says "a minimal grade of 1 to 2 is not considered significant. However, a grading score of 3 or above is uniformly reproducible and considered positive." So each of those cetyl readings has to be read under the threshold its own paper printed, and they land on opposite sides of their respective lines. Neither is a second opinion. Both are Fulton. HERE IS THE THING THIS PAGE EXISTS TO SAY. Outside Fulton's laboratory we identified two documents that examine any member of this family for comedogenicity — two is what our searching turned up, not a census of the literature — and both of them land on the same two materials. The first is the Cosmetic Ingredient Review's 1985 final report on stearyl alcohol, oleyl alcohol and octyl dodecanol, in the Journal of the American College of Toxicology, volume 4, number 5. Its section headed "Comedogenicity" is one sentence long, and this is the sentence 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 attached to it is Kligman and Mills, "Acne cosmetica", Arch Dermatol 106(6), 1972 — a paper we have not obtained, so the result reaches us at second hand. Two rabbits, no score, no scale. And the asymmetry inside that report is worth more than the sentence itself. It assesses three materials, two of which are in this family, and the comedogenicity section names only one of them. Its summary says "A rabbit ear comedogenicity test on Stearyl Alcohol was negative" and stops. Oleyl alcohol is not mentioned there at all. The same report is perfectly capable of flagging a gap when it wants to — on mutagenicity its summary states that "Oleyl Alcohol and Octyl Dodecanol were not tested in these assays" — and on comedogenicity it says nothing of the kind. Meanwhile the abstract's comedogenicity sentence sits immediately after a sentence about what "these alcohols" did in rabbit irritation tests. A result for one material, printed next to a plural, in a document whose conclusion clears all three as safe: that is the shape a family-level misreading starts from, and we found it in a final report rather than on a chart. The second is Nguyen, Dang and Maibach's 2007 rabbit study in Cutaneous and Ocular Toxicology, on a 0-to-4 scale. Its abstract lists fourteen materials — cetyl alcohol tenth, stearyl alcohol twelfth — and then says: "The first nine were deemed positive." Neither is among the nine. The ordinals are softer than they look — the abstract prints "stearyl alcohol sodium lauryl sulfate (SLS)" with no comma in it, and where one name ends and the next begins decides both the count and where stearyl alcohol falls in it. Only "not among the first nine" comes through that ambiguity intact. We have not read its table, and no per-material figure appears in what we have read, so what it gives is a classification and not a measurement. So: both documents from outside Fulton's laboratory landed on materials he had already put in his borderline band, neither gave us a figure in what we have read of it, and both point the reassuring way. Of the two materials the family's higher ratings rest on, we identified no reading at all by anyone other than Fulton. Morris and Kwan's 1983 survey — the other 0-to-5 rabbit-ear paper, and the one that contradicts Fulton in print on other materials — has no row for any of these five. That is the family-level fact: the checking has all happened at one end of the family, and it is the end where the stakes are lowest. One exception sits inside our own generalisation, and it should be stated rather than tidied away. Cetearyl alcohol scores 2 of 5, and we identified no second document that examines it for comedogenicity at all. So "the 2s were looked at again" is true of cetyl and stearyl alcohol and not of the third.

What the evidence doesn’t tell you

This is a claim about who produced the numbers, not about whether they are right. An unchecked reading is not a wrong reading, and the 4s are not made worse by the absence of a second one. They are simply less examined than the numbers beneath them, and a chart that prints 2, 2, 2, 4, 4 in one column conceals that. The two non-Fulton documents both point downward, and it would be easy to read the paragraph above as reassurance about cetyl and stearyl alcohol. It is not, and we would not accept either document as evidence if it pointed the other way. One is a single sentence about two rabbits, reported at second hand from a 1972 paper we have not obtained. The other is an absence from a list of positives, in a paper whose table we have not read. An unnumbered verdict does not resolve a numbered borderline. All of it is the rabbit ear, and the objections do not stop applying because a number is low. Fulton called his own survey "not at all definitive but simply designed to stimulate research", and warned that the model is so sensitive that "not everything that irritates this model will also irritate human skin". A 2025 JAAD Reviews survey of the field found that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated claim. We identified no study that counted comedones on human skin after applying any of these five materials, in the documents we hold and in the searches run for their pages. The human exposure work we are aware of in this family was run for irritation and sensitisation, which are different endpoints and are not scored in comedones. An unrecorded comedone is not an absent one. There is a pattern in the five numbers, and there is a line we will not cross in describing it. Cetyl alcohol at 2 of 5 and isocetyl alcohol at 4 of 5 are the same C16 formula in two arrangements; stearyl alcohol at 2 of 5 and oleyl alcohol at 4 of 5 are both C18. It is tempting to turn that into a rule about branching and unsaturation. We are not going to, and the reason is on the record: we once built a structural argument about this exact family — a molecular-weight penetration window — and simple arithmetic refuted it. What the table supports is two pairs of single readings, one laboratory, no replication. Fulton offers no mechanism for it in the passages we have read, and branching and unsaturation are not established predictors of comedogenicity in anything we found. Finally, the honest caveat about the page itself. Generalising across a family is what a hub is for, and it is also the claim type this site exists to distrust, including when we are the ones making it. The generalisation here is deliberately narrow — it is about which documents exist, not about what these materials do to skin — and it already has an exception inside it, in cetearyl alcohol. If a reading of isocetyl or oleyl alcohol from another laboratory turns up, the argument on this page is over, and we would rather say so now than be shown it later. One thing this family is not short of evidence on, and it is a different question entirely: several of these alcohols are recognised contact allergens with a real patch-test literature. Allergy is not comedogenicity. Where an ingredient lands on this site says nothing about whether it is the reason someone cannot use most of the creams in a pharmacy.

All 5 fatty alcohols we rate

The legacy score is printed exactly as it appears in the paper, including the ranges, the asterisks and the parentheses. Those marks are not decoration. They are the paper telling you what its own number is worth.

Sources

  1. Fulton JE. "Comedogenicity and irritancy of commonly used ingredients in skin care products." J Soc Cosmet Chem 40:321-333 (1989) The source of every one of this family's five numbers, read off the journal scan and transcribed at 400dpi because OCR drops the numeric columns. Design — ingredient at 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 measured with a micrometer. Scale 0 to 5. All five rows were transcribed one row at a time, with no section heading recorded over any of them — the transcription holds headings for only two blocks of that paper. What it cannot support — Fulton calls the 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 own grades so that 2 is "borderline" rather than positive. It is one laboratory's animal assay at a concentration and under an occlusion regime no product reproduces.
  2. Fulton JE Jr, Pay SR, Fulton JE III. "Comedogenicity of current therapeutic products, cosmetics, and ingredients in the rabbit ear." J Am Acad Dermatol 10(1):96-105 (1984) Fulton's earlier rabbit-ear survey, read in full off the journal scan. It is the second reading for two members of this family and for nobody else in it — oleyl alcohol 4, agreeing with 1989, and cetyl alcohol 3, one grade above it. Cited here chiefly for its KEY, which is not the 1989 key: "a minimal grade of 1 to 2 is not considered significant. However, a grading score of 3 or above is uniformly reproducible and considered positive." A number from this paper and a number from the 1989 paper cannot be compared without carrying each paper's own threshold. What it cannot support — it is the same investigator, so two agreeing readings are internal consistency, not independent replication.
  3. 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, amended-tentative or comment-only draft — the cover page reads "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, and the document carries no draft-status line anywhere. It is an industry-funded, independently panelled toxicological safety review, and its question is safety rather than comedogenicity. Its entire Comedogenicity section is the single sentence quoted on this page, about stearyl alcohol only, referenced to Kligman and Mills 1972 — a paper we have not obtained, so we carry the result second-hand and carry no number, because none is printed. What it cannot support — it reports no comedogenicity result for oleyl alcohol, does not say that none exists, and concludes all three materials safe as used. Safety is not noncomedogenicity, and a conclusion covering three ingredients does not convert a finding about one of them into a finding about the others.
  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-ear assay from a different laboratory, on a 0-to-4 scale — a third scale, which is why nothing from it can be set beside a Fulton digit. We have read the abstract verbatim and not the table. It lists fourteen materials, cetyl alcohol tenth and stearyl alcohol twelfth on a reading that has to supply a comma the abstract does not print, in "stearyl alcohol sodium lauryl sulfate (SLS)". It states "The first nine were deemed positive." What it therefore supports, and all it supports, is that neither was placed in that set. What it cannot support — no per-material figure appears in anything we have read of it, so this is a classification and not a measurement, and it says nothing about the other three members of this family, which it did not test.
  5. 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) The other major rabbit-ear survey on the same 0-to-5 scale, six years before Fulton's table: undiluted material unless stated, three rabbits, 14 applications, microscopic grading, 32 rows covering lanolins, vegetable oils, esters and surfactants. Cited entirely for what it does not contain — not one of the five materials on this page has a row in it. It matters because this is the paper that openly contradicts Fulton in print on other materials, so its silence here is the reason "Fulton scored it 2" cannot be read as "the literature agrees".
  6. "Comedogenicity in cosmeceuticals: a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) A peer-reviewed narrative review of the field from 1972 to 2025. It finds that no standardised comedogenicity test exists and that the "non-comedogenic" claim is unregulated. A synthesis rather than new data, and not independent of the legacy assays in the sense of testing anything — but independent of the consumer lists that reprint them, and it applies to the low numbers on this page exactly as hard as to the high ones.

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