Olive Oil
Olive oil is rated Caution, on thin and divided evidence. The two rabbit-ear assays we can find that tested it disagree — Fulton scored it a borderline 2, Morris and Kwan scored it 0 — and we found no study that counted comedones on a human face.
High in oleic acid; commonly cautioned for acne-prone skin despite a modest legacy score.
Sources disagree: Fulton 1989 printed 2(1) of 5; Morris and Kwan 1983 printed 0 of 5 for the same named oil. Two labs, two answers, neither key shared.
What it is
Olive oil is the oil pressed from the fruit of Olea europaea. It is a triglyceride oil, and the feature that matters most on this page is that it is dominated by a single fatty acid. Under the International Olive Council's trade standard, oleic acid — a monounsaturated C18:1 fatty acid — makes up between 55 and 83 percent of it, with palmitic acid at roughly 7.5 to 20 percent and linoleic acid at 2.5 to 21 percent. That composition shifts with cultivar, ripeness and growing climate, which is the practical form of Fulton's own footnote on oils: results "depend on source of raw material." In cosmetics olive oil is used as an emollient and skin-conditioning oil, and it carries a long domestic history as a cleansing and massage oil applied straight from the bottle. On a label it appears as Olea Europaea (Olive) Fruit Oil.
Why we rate it Caution
We rate olive oil Caution, at Low confidence — and the confidence is low because the only comedogenicity evidence we could trace for it is two old rabbit-ear assays that do not agree. Fulton's 1989 table has an olive oil row. Unlike coconut oil, this is a reading of the actual material, not a number borrowed from a neighbouring row: Fulton scored olive oil 2 on his 0-to-5 scale. Two things travel with that 2 and are almost always dropped. First, Fulton's own grade key: 0-1 is "not considered significant," 2-3 is "borderline," 4-5 is "considered positive." A 2 is the bottom of borderline — not a clean result, and not a positive one. Second, the figure in parentheses on the row. Fulton printed it as "Olive oil 2(1)," and in his notation the parenthetical is the score for the refined oil. Refined olive oil scored 1 — back down in "not significant." The whole row sits in his section "VI. Oils," which carries one footnote: "Results depend on source of raw material." So even inside a single paper, olive oil's number is not a single number. The other primary assay disagrees outright. Morris and Kwan, six years earlier, using the same 0-to-5 rabbit-ear method, scored olive oil 0 — applied undiluted. That is the same scale as Fulton's, run in a different laboratory, landing at the opposite end of the "not significant" band. Morris and Kwan are not republishing Fulton; theirs is an independent primary paper that contradicts him in print on several materials. On olive oil, the two papers we could trace that put it on a rabbit's ear came back with a borderline 2 and a flat 0. Two other rabbit assays we hold do not test it at all: Fulton's earlier 1984 survey with Pay and Fulton has no olive oil row, and neither does the 2007 Nguyen, Dang and Maibach study. The Caution does not rest on a strong signal, then. It rests on one borderline legacy reading — halved for refined oil — set against a zero, plus the fact that olive oil is mostly oleic acid, which has a comedogenic reputation of its own. That reputation is real, and it is also the part most easily overstated; the limits section below is where it has to be handled carefully.
What the evidence doesn’t tell you
What none of this measured is olive oil on a human face. We identified no study that assessed the comedogenicity of olive oil in people — no comedone counts, no follicular biopsies, on any human skin. The rating is built entirely on two rabbit-ear assays from the 1980s: a model that scores follicular keratosis in a rabbit's ear, not acne on a person. There is human data on olive oil and skin, and it is important not to let it stand in for comedogenicity, because it measured something else. Danby and colleagues (2013) applied olive oil to the forearms of adult volunteers, twice a day for several weeks, in two randomised forearm-controlled cohorts, and found that it significantly reduced the integrity of the stratum corneum and produced mild redness — while sunflower oil, on the same volunteers, did not. That is a skin-barrier finding, and the authors read it as relevant to eczema, not acne. A weakened barrier is not a blocked follicle; erythema is not a comedone. The study shows olive oil can be hard on the barrier. It does not show whether it clogs pores, because it did not look for a comedone. The oleic-acid argument needs the same discipline. Olive oil is more than half oleic acid, and oleic acid is genuinely implicated in follicular trouble: Motoyoshi (1983) showed that free oleic acid — and, more strongly, its oxidation peroxides — induced sizeable comedones in rabbit ear skin. But that experiment tested free oleic acid, not olive oil. In olive oil the oleic acid is bound into triglycerides, not free, and "the fatty acid is comedogenic in isolation" is not the same claim as "the oil is comedogenic." The distinction is exactly the one this site exists to keep: a property of a component is not automatically a property of the material that carries it. We note the oleic-acid mechanism because it is real and because it is why many clinicians caution against olive oil; we do not treat it as a measurement of what olive oil itself does. Finally, "olive oil" is not one fixed material. Extra-virgin, refined and pomace grades differ in free fatty-acid content and in how oxidised they are, and Fulton's own refined-versus-unrefined split — 2 dropping to 1 — shows the grade alone can move the number. A rating given across "olive oil" is a rating given across a range.
Where you’ll see it
On an ingredient list it is Olea Europaea (Olive) Fruit Oil. It appears in facial and body oils, cleansing and massage oils, soaps, balms and some traditional and "natural" moisturisers, and it is a common base for oil cleansing. It is also a kitchen staple that people apply to skin neat, which is the form most of the human observation above was done on. Where it sits on an ingredient list tells you little on its own: grade and freshness — extra-virgin versus refined, fresh versus oxidised — matter more to this page's question than label position does, and neither is printed on the label.
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 rabbit-ear assay nearly every online comedogenic score descends from, read here off a render of the journal scan rather than from a list quoting it. Method: ingredient at roughly 10% in propylene glycol, applied to the inner ear of three New Zealand albino rabbits, follicles scored for keratosis on a 0-to-5 scale with the key 0-1 "not significant," 2-3 "borderline," 4-5 "positive." It contains a real olive oil row — "Olive oil 2(1)" — where the 2 is the crude oil and the parenthetical 1 is the refined oil, both inside Section VI "Oils," whose footnote reads "Results depend on source of raw material." A borderline reading, not a positive one, and not a single number.
- 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 primary rabbit-ear assay on the same 0-to-5 scale as Fulton's and predating it by six years — not a republisher of Fulton, and one that openly contradicts him in print on several materials. It scored olive oil 0, applied undiluted. Cited as the second of the two primary readings we could trace, and the reason its number is a disagreement rather than a finding. The score is taken from our verbatim transcription of the paper's oils table, which is printed rotated and is lost to OCR.
- Danby SG, Alenezi T, Sultan A, et al. "Effect of olive and sunflower seed oil on the adult skin barrier: implications for neonatal skin care." Pediatr Dermatol 30(1):42–50 (2013) A human study, and cited precisely because it is not a comedogenicity study. Adult volunteers, with and without a history of atopic dermatitis, in two randomised forearm-controlled cohorts, applied olive oil (and, in one cohort, sunflower oil) twice daily for several weeks. Its endpoints were stratum-corneum integrity, transepidermal water loss and erythema — barrier measures. Olive oil significantly reduced barrier integrity and caused mild redness; sunflower oil did not. It counted no comedones and looked at no follicles. Cited to mark the line between "hard on the skin barrier" and "comedogenic," which are different findings.
- Motoyoshi K. "Enhanced comedo formation in rabbit ear skin by squalene and oleic acid peroxides." Br J Dermatol 109(2):191–198 (1983) A rabbit-ear study of free oleic acid, squalene, isopropyl myristate and others, together with their oxidation peroxides. Free oleic acid, and more strongly its peroxides, induced sizeable comedones, with comedone size tracking peroxide level. Cited for the oleic-acid mechanism behind olive oil's reputation — and cited with its material-identity caveat stated: it tested free oleic acid, not olive oil, in which the oleic acid is bound into triglycerides. Evidence about the component, not about the material.
- International Olive Council. "Trade Standard Applying to Olive Oils and Olive Pomace Oils" (COI/T.15/NC No 3/Rev. 20, 2024) The trade standard that defines olive oil's permitted composition, cited only for the fatty-acid figures on this page: oleic acid 55.0-83.0%, palmitic 7.5-20.0%, linoleic 2.5-21.0%. An identity-and-authenticity standard, not a skin or comedogenicity source; it says nothing about pores. Used to establish that olive oil is oleic-acid-dominant, and that its composition is a range rather than a constant.
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