Oleth-3
Oleth-3 is one of the ingredients whose circulating comedogenic number is printed against its own name rather than borrowed from a neighbour: Fulton's 1989 rabbit-ear assay scored it 5, the top of his scale. Unlike laureth-4, though, it appears in one paper only — a single three-rabbit experiment, with no second laboratory and no human test — and the same table shows the score falling as the molecule is ethoxylated further.
Ethoxylated oleyl alcohol, nominally ~3 EO units; Fulton 1989 scored 5 in one experiment.
What it is
Oleth-3 is a nonionic surfactant made by attaching a short chain of ethylene-oxide units to oleyl alcohol — the eighteen-carbon, singly-unsaturated fatty alcohol derived from oleic acid. On a label it is Oleth-3, and the "3" is a nominal average of approximately three ethylene-oxide units, not a fixed count: a commercial oleth-3 is a distribution of chain lengths around that average, and Fulton records nothing about the composition, supplier or distribution of the sample he tested. The Cosmetic Ingredient Review's 1999 assessment of the Oleth family describes them as surfactants used as emulsifying, cleansing and solubilising agents. In a formula a lightly ethoxylated oleth like this one is usually pulling an oil phase into water — it is the kind of emulsifier that lets an oil go on and rinse or spread as a milk — which is why it turns up in cleansing oils, makeup removers and some emulsion creams. It has close relatives on the same shelf, and their identities are worth keeping apart, because the legacy table treats them very differently. Oleth-5, Oleth-10 and Oleth-20 are the same oleyl alcohol carrying more ethylene-oxide units, and each is a separate ingredient with its own score. Oleth-3 phosphate is a different molecule again. Oleyl alcohol is the parent, before any ethoxylation. Only one of these — Oleth-3 itself — carries the 5.
Why we rate it Clogging
We rate it Clogging, at Low confidence, and this page is unusual in the same way the laureth-4 page is: the number is real. Most of the scores this site takes apart turn out to belong to a different material — a neighbouring row, a derivative, a dropped word. Oleth-3's does not. Fulton's 1989 table — the source of nearly every comedogenic number in circulation — prints Oleth-3 at 5 on his 0-to-5 scale. We read the row off a transcription of Table I rather than off a chart quoting it, and the printed name is unambiguous: the row is Oleth-3, not Oleth-5, not Oleth-3 phosphate (which he scores 2), not the parent oleyl alcohol (which he scores 4). It matters what a 5 is in Fulton's own words, because the charts that publish his numbers leave his key out: "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." And he defines the top of the scale by a reference substance: "Grade 5 is the presence of large comedones throughout the ear, similar to those induced by the application of our standard 'positive' testing agent, isopropyl myristate." So a 5 here means the material produced follicular keratosis on the scale of isopropyl myristate, the comedogen Fulton anchored his high end to, in this assay. One thing his table shows, and only shows. Within his own oleth rows the lightly ethoxylated Oleth-3 scored 5, Oleth-5 scored 3, Oleth-10 scored 2 and Oleth-20 scored 1; his laureth pair runs the same direction, Laureth-4 a 5 and Laureth-23 a 3. Reading down those rows, the more ethylene-oxide units on the molecule, the lower the score. That is a pattern printed in the table, not a law and not a mechanism — his steareth rows do not fall cleanly in order, and his own note on lanolin additives runs the other way — so we report it as a set of rows and leave it there. What it does establish is narrower and worth saying: Oleth-3 is the most lipophilic, least ethoxylated member of its own series, and it sits at the top of that series' scores.
What the evidence doesn’t tell you
Everything above happened inside the ear of a rabbit: the ingredient at roughly 10% in propylene glycol, 1 ml applied to the inner ear of three New Zealand albino rabbits, five days a week for two weeks, follicles then scored for keratosis. It is not a human face, not a finished formula, and not a realistic in-use concentration. We identified no human comedogenicity study of oleth-3 — not on a face, not on a back, not with a comedone count anywhere. And it was read in one experiment. This is where oleth-3 is weaker than an ingredient like laureth-4, whose legacy 5 Fulton recorded twice — a 5 in 1989 and a 4 in his earlier 1984 paper. We hold Fulton's 1984 rabbit-ear table in full, and it has no oleth row at all; the oleth series appears only in 1989. So there is no second Fulton reading of this material to compare against, and Morris and Kwan — whose 1983 assay ran on the same 0-to-5 scale and who were willing to contradict Fulton in print — did not test it; nor did Nguyen, Dang and Maibach in 2007, whose fourteen materials include no oleth. We identified no non-Fulton measurement of oleth-3's comedogenicity in the corpus we hold or the searches we ran. The 5 comes from one three-rabbit experiment in one laboratory, and that is the whole of the numeric record. A neighbouring finding is easy to mistake for a comedogenicity one, so we will name it and then set it aside. The CIR review describes oleyl surfactants as skin-penetration enhancers, citing work by Kadir and colleagues on stratum-corneum permeability; that is a statement about the class, on studies we have not read in full, and not a test of oleth-3 itself. Increasing how much of something crosses the outer skin is a different endpoint from plugging a follicle, and nothing we found connects the two for oleth-3. Penetration-enhancement data is not comedogenicity data, and we are not going to borrow it as if it were. Fulton rejected the low-concentration defence in general — his conclusion says "we are not convinced of the statement that lower concentrations of these compounds can be safely used with no comedogenic consequences" — but that sentence names isopropyl myristate, acetylated lanolin alcohol and lauric acid derivatives such as laureth-4, and it does not name oleth-3, which is an oleyl-alcohol derivative rather than a lauric one. He published no dose-response curve for oleth-3, and we identified no study establishing a percentage below which it stops producing comedones in the assay. Finally, the field-wide caveat that sits under every legacy score on this site: the rabbit-ear model has been questioned since Frank's 1982 paper, and a 2025 review in JAAD Reviews, surveying the literature from 1972 on, found that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. That is a remark about the standards of this subject, and it applies to oleth-3's 5 exactly as it applies to everyone else's numbers.
Where you’ll see it
On a label it is Oleth-3. The CIR's 1999 report on the Oleth family records their use as emulsifying, cleansing and solubilising surfactants; in practice a lightly ethoxylated oleth like this one shows up most visibly in cleansing oils, oil-based makeup removers and some emulsion creams and lotions, where its job is to let an oil phase disperse in water. Those are illustrative categories, not a measured prevalence — we have not audited the market — and we are not going to tell you where it sits on an ingredient list, because label position is not a dose. Its ethoxylate relatives are separate entries here with their own scores, and — per Fulton's own table — not the same score: the more heavily ethoxylated members of the oleth series (Oleth-5, Oleth-10, Oleth-20) read progressively lower than Oleth-3. Oleth-3 phosphate and the parent oleyl alcohol are different materials again.
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.
- Fulton JE. "Comedogenicity and irritancy of commonly used ingredients in skin care products." J Soc Cosmet Chem 40:321–333 (1989) The primary source of our legacy score and of nearly every comedogenic number in circulation. Method: the 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, follicles scored for keratosis on a 0–5 scale. Read off a transcription of Table I, not off a chart quoting it. It prints Oleth-3 at 5 — a row carrying this exact printed name, not a neighbour's — alongside Oleth-5 3, Oleth-10 2, Oleth-20 1 and Oleth-3 phosphate 2, and the laureth pair (Laureth-4 5, Laureth-23 3). It supplies the grade key the charts omit ("0 to 1 not significant, 2 to 3 borderline, 4 to 5 positive") and defines grade 5 as comedones "similar to those induced by isopropyl myristate." Its conclusion names "the major offenders" — isopropyl myristate, acetylated lanolin alcohol and lauric acid derivatives such as laureth-4 — and does NOT name oleth-3. A rabbit-ear assay, and the author himself called the survey "not at all definitive but simply designed to stimulate research."
- Fulton JE, 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 paper, on the same 0–5 scale. Cited here for what it does NOT contain: it has no oleth row at all — the oleth series appears only in the 1989 survey — which is why this page can say the 5 was read only once. It is the reason oleth-3's number is thinner than laureth-4's, which Fulton did record in both papers. We hold its Table I in full; the absence is verified, not assumed.
- 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, six years before Fulton, from a different laboratory and on the same 0-to-5 scale: thirty-two materials, three rabbits, ear canal, undiluted unless stated, 14 applications, microscopic grading. Cited for an absence we verified against its full table — no oleth of any length appears among its thirty-two rows, and neither does oleyl alcohol. The one corpus that has contradicted Fulton in print, on sodium lauryl sulfate, simply never tested this material, so its silence is neither support nor challenge.
- 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 on a 0-to-4 scale, abstract read via EuropePMC; the full text and its per-material scores were not read, so no number is carried from it. Cited only for what its fourteen named test materials do NOT include: no oleth, and no ethoxylated surfactant of any kind. It neither confirms nor disputes the 5.
- Andersen FA. "Final Report on the Safety Assessment of Oleth-2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -15, -16, -20, -23, -25, -30, -40, -44, and -50." Int J Toxicol 18(2 Suppl):17–24 (1999) A Cosmetic Ingredient Review Expert Panel safety assessment of the Oleth family — an industry-structured review programme, not an unaffiliated one — and NOT a comedogenicity assessment. Cited only for what it actually establishes: that oleths are surfactants used as emulsifying, cleansing and solubilising agents, and that the Panel concluded Oleth-2 through -50 safe in the present practices of use. It assesses safety, not pore-plugging — a different question — and it notes two things a comedogenic page might otherwise borrow wrongly: that these ethoxylates can carry 1,4-dioxane and ethylene-oxide impurities (a purity matter, not a comedogenicity one), and that oleyl surfactants act as skin-penetration enhancers (a permeability endpoint, not a follicular one). Free-access final report; status read from its cover.
- "Comedogenicity in cosmeceuticals: a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) Recent peer-reviewed review of the whole field, covering the literature from 1972 onward. It is a synthesis of the legacy literature, not a new measurement, and independent of Fulton only in authorship — the corpus it reviews includes his. Finds that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. Cited for the field-wide caveat that sits under every legacy score on this site, oleth-3's included.
Others in the same family
Ethoxylates (PEGs & polysorbates) 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 ethoxylates (pegs & polysorbates) as a family ›
Last reviewed 2026-08-05 · How we decide