Sesame Oil
Sesame oil is rated Caution, and the comedogenic 3 that follows it around is Fulton's primary sample, whose processing state he does not print — the same cell scores refined sesame oil a 1, and a second laboratory printed a 1 for its own sesame oil row six years earlier. Within Fulton's paper, refining moved the number down.
Occlusive seed oil with a moderate legacy clog score.
What it is
The oil pressed from the seed of Sesamum indicum. On a label it is Sesamum Indicum Seed Oil. It is a triglyceride seed oil used as an emollient and as a carrier or massage oil, and it reaches the skin in two quite different states: cold-pressed or toasted unrefined oil, which keeps its colour, odour and minor plant components, and refined oil, which has been stripped of most of them. That distinction is not cosmetic trivia here. It is the reason Fulton's table prints two numbers for this oil in a single cell, and it is the reason the rating is Caution rather than Clear or Clogging.
Why we rate it Caution
We rate it Caution at Low confidence. The confidence is Low because the only measurements that exist are rabbit-ear assays from the 1980s, and we say so plainly: this is a legacy-assay rating, not a human one. Unlike many of the oils whose scores are quoted from Fulton, sesame oil is genuinely in his table. We rendered Table I of the 1989 paper and read it by eye, and Section VI, "Oils," has a sesame oil row. The famous number is real. What the lists drop is what is printed alongside it. The cell Fulton prints for sesame oil is, verbatim, 3(1)**. His key defines the parentheses: the whole number is the comedogenicity grade, and "parentheses indicate results using refined oil." The section heading above it, "Oils*", carries a single asterisk whose footnote reads "results depend on source of raw material." What the second mark on this cell denotes we have not resolved — our transcription records it and defines only the single one, and we are not going to guess. So the paper is not saying sesame oil is a 3. It is saying the sample he tested scored 3 — and he does not print whether that sample was refined or unrefined — while the refined grade scored 1. By Fulton's own published key a grade of 2 to 3 is "borderline" and a grade of 0 to 1 is "not considered significant", so inside this one table, in one lab, sesame oil crosses from borderline to not-significant with refining. Fulton then does the thing almost nobody quoting him does: he explains it. In the body of the paper he writes, naming this oil specifically, "Among the natural oils such as sesame oil, avocado oil, and mink oil, the results are improved when a more refined oil is used." The parenthetical 1 is not an aside. It is the finding, stated twice — once in the table and once in the prose. There is a second measurement, and it is independent. Morris and Kwan, in 1983, six years before Fulton and in a different laboratory, ran a rabbit-ear assay on the same 0–5 scale. Their table has a "Sesame Oil" row, and it reads 1. We do not hold Morris and Kwan's verbal key, so we report their number as what it is — a 1 on their 0–5 scale — and do not put one of Fulton's band labels on it. Their row prints no refining state either. So the numbers coincide with Fulton's parenthetical 1 and differ from his 3; what we cannot say is that the two laboratories put the same material in the ear. Caution is the honest word for that. It is not Clear, because a borderline 3 is on record and Fulton did not dismiss it. It is not Clogging, because nothing anyone measured put sesame oil in the 4-to-5 band Fulton called "positive." It sits in the middle because the evidence itself sits in the middle, and because in Fulton's hands the number moved with refining.
What the evidence doesn’t tell you
Every number on this page came from a rabbit's ear, and the two ears were not treated alike. Fulton put the oil at roughly 10% in propylene glycol on the inner ear of New Zealand albino rabbits, five days a week for two weeks, then scored follicles for keratosis under a micrometer. Morris and Kwan applied their materials undiluted, in the ear canal, over 14 applications, and graded the follicles microscopically. Neither is a human face and neither is a finished formula, and we hold no measured in-use concentration for sesame oil to set either regime against. Fulton called his own survey "not at all definitive but simply designed to stimulate research." We identified no human comedogenicity study of sesame oil — no trial that put it on faces and counted comedones. The consumer and clinic sources that discuss it are discussing the same 1980s rabbit numbers. Nor is the oil in every legacy table: Fulton's earlier 1984 rabbit-ear paper has no sesame oil row, and Nguyen, Dang and Maibach's 2007 rabbit study does not list it among its test materials. Both absences are verified against the papers. So the specific claim we can stand behind is narrow: two rabbit-ear assays measured a sesame oil, Fulton returned 3 for his primary sample and 1 for refined oil, Morris and Kwan returned 1, and we found no test of the question on human skin. The refinement finding is real but it is not a dose-response curve. Fulton reports one refined result and one result whose processing state he does not give; he does not report a graded series, a supplier, or what "refined" meant in his hands. A reader cannot read a precise number off the back of a particular bottle from this. What his comparison supports is a direction inside his own paper — refining lowered the score — not a rule and not a threshold. The rabbit-ear assay itself has been challenged for decades. Draelos and DiNardo's 2006 re-evaluation in the Journal of the American Academy of Dermatology tested finished products on human skin and found isolated rabbit-ear ingredient scores a poor guide to what a product does on a person; it was a study of formulations, not a human re-test of sesame oil, and should not be read as one. A 2025 review in JAAD Reviews found that no standardised comedogenicity test exists at all and that "non-comedogenic" is an unregulated label. Those caveats apply to the 1 exactly as much as to the 3.
Where you’ll see it
On a label it appears as Sesamum Indicum Seed Oil. It is used as a carrier and massage oil — it is the base oil of much of traditional Ayurvedic massage — and turns up in facial and body oils, cleansing oils and balms, and some soaps and hair products. It reaches skin both as unrefined (cold-pressed or toasted) oil and as refined, largely odourless oil, and a label rarely tells you which. Given that Fulton's two numbers moved with exactly that distinction, the grade of oil is worth more attention than the position of the word on the list, and we are not going to infer a concentration from where it sits.
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 nearly every comedogenic score in circulation, and one of only two that actually measured sesame oil. Read off a render of the journal scan rather than via a list quoting it. Method: ingredient at roughly 10% in propylene glycol, inner ear of New Zealand albino rabbits, a few rabbits per assay, follicles scored for keratosis. Section VI, "Oils*," prints sesame oil verbatim as 3(1)**, under a section footnote reading "results depend on source of raw material." Fulton's key defines the parenthetical: it is the score for the refined oil. It does not define the second mark on this cell, and neither do our files, so we print the cell and leave the mark unexplained. He does not state the processing state of the sample scored 3. The body text names this oil directly — "Among the natural oils such as sesame oil, avocado oil, and mink oil, the results are improved when a more refined oil is used." Grade key: 0–1 "not considered significant," 2–3 "borderline," 4–5 "considered positive."
- 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 independent rabbit-ear assay on the same 0–5 scale, six years before Fulton 1989 and in a different laboratory — not a republisher of him. Morris and Kwan openly contradict Fulton on other ingredients and say so in print, which is why their agreement matters when it happens. Their table scores "Sesame Oil" 1, on their own 0–5 scale, with no refining state printed and no verbal key in our hands to band it with. The number coincides with Fulton's parenthetical 1 and differs from his 3; the materials behind the two rows cannot be shown to be the same. Cited for that single row.
- "Comedogenicity in cosmeceuticals — a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) A recent peer-reviewed review of the field, covering the literature from 1972 onward. Finds that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. It is a synthesis of the legacy literature, not a new measurement, and independent of Fulton only in authorship, since the corpus it surveys includes his. Cited for the field-wide caveat that applies to sesame oil's low and high numbers alike, not for any sesame-specific result.
- acne.org comedogenic ingredient list A widely quoted consumer list, and one of the places a reader will have met a sesame oil number. Not an independent measurement: the comedogenic scores it circulates descend from the 1980s rabbit-ear assays above. Listed so the reader can see where the figure they arrived with came from, and that it is the same assay, not a separate confirmation of it.
Others in the same family
Oils 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 oils as a family ›
Last reviewed 2026-08-12 · How we decide