Hydrogenated Vegetable Oil
Hydrogenated vegetable oil is one of the ingredients whose legacy number is real, printed and checkable — and also one of the weakest-supported on the list. Fulton's 1989 rabbit-ear assay scored it 3 of 5, a grade he himself filed as "borderline." It is the only assay that carries it: the second major rabbit corpus tested nine vegetable oils and none of them was this one, and we identified no human comedogenicity study. The score also describes a material that is not a single substance — "hydrogenated vegetable oil" is a process applied to an unnamed feedstock.
Hardened vegetable fat; Fulton 1989 scored 3, borderline by his key, in one experiment.
What it is
A vegetable oil — the label does not say which — that has had hydrogen added across its fatty-acid double bonds in the presence of a catalyst, turning a liquid oil into a white-to-pale-yellow waxy solid that melts on contact with skin. On an ingredient list it is Hydrogenated Vegetable Oil (CAS 68334-28-1; EINECS 269-820-6). The SpecialChem INCI directory lists its cosmetic functions as emollient and skin-conditioning agent and describes it as a thickener that gives lotions, creams, lip balms and lipsticks their body and a longer shelf life than an unhydrogenated oil. The colour, texture and melting range it gives — a white-to-pale-yellow waxy solid melting at 32–46 °C — are vendor specifications for commercial grades, not a property of a defined substance; different source oils and different degrees of hydrogenation give different figures. The word "vegetable" is doing a lot of quiet work: the same INCI name covers hydrogenated coconut, palm, soybean and other oils, and partial versus full hydrogenation gives materially different fats (partial hydrogenation leaves trans fats behind). So the name on the label is a category, not a recipe — which matters below, because the one comedogenic score attached to it was measured on a single, unspecified sample.
Why we rate it Caution
We rate it Caution, on a single rabbit-ear assay. This is not one of the fabrication cases on this site: the number is really there in the primary table, attached to this exact printed row, and it is the number our own rating rests on. Fulton's 1989 table — the source nearly every comedogenic number online descends from — prints "Hydrogenated vegetable oil" at 3, in section VI, "Oils." We read the row off a render of the journal scan rather than off a list quoting it, and it is a bare 3, with none of the parenthetical "refined-oil" second figures that Fulton prints beside some of its neighbours (avocado 3(2), olive 2(1), almond 2(1)). What a 3 meant to Fulton is the part the republishing charts drop. His own key reads: "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." So this is the top of the borderline band — above "not significant," below the range Fulton was willing to call a positive result. It sits in the same asterisked section as cocoa butter (4) and coconut butter (4), and the asterisk on that section heading is defined once in the paper: "Results depend on source of raw material." On a material whose name does not even fix which oil was hydrogenated, that caveat is not a footnote — it is most of the story. What we do not have is a second reading, and we looked. Morris and Kwan, publishing an independent rabbit-ear assay six years earlier on the same 0-to-5 scale, tested nine vegetable oils — olive, avocado, castor, corn, sesame, safflower, peach kernel, grape seed and sweet almond — and hydrogenated vegetable oil was not among them. Fulton's own earlier 1984 table, which we hold in full, has no row for it either. Nguyen, Dang and Maibach's 2007 rabbit assay names fourteen materials and this is not one of them. No independent replication under this exact printed name was identified in the corpus we hold or the searches we ran. Where corn oil has two laboratories that disagree and castor oil has two that concur, hydrogenated vegetable oil has one lab and one number. Caution reflects that single borderline reading, and nothing sturdier stands behind it.
What the evidence doesn’t tell you
We identified no human comedogenicity study of hydrogenated vegetable oil in the reviewed search — not on a face, not on a back, not with a comedone count. The rating stands on a single three-rabbit experiment, at roughly 10% in propylene glycol, with follicular keratosis scored under a microscope. Fulton called his own 220-row survey "not at all definitive but simply designed to stimulate research," and warned that the rabbit ear is sensitive enough that "not everything that irritates this model will also irritate human skin." A single borderline grade from one unnamed batch, read once, is a long way from a measurement of the material in a given product. The identity problem is sharper here than for a named oil. Fulton records no supplier, no source oil and no degree of hydrogenation for the sample he tested, and "hydrogenated vegetable oil" is not one substance — it is coconut, palm, soybean or another oil, fully or partially hardened. His section footnote, "results depend on source of raw material," was written for oils whose species was at least named; applied to a category term it bites twice, because the raw material is unspecified at two levels at once. The 3 describes whatever was in Fulton's jar. It does not transfer cleanly to the hydrogenated oil in the bottle in front of you, and we cannot say how far the two are apart. There is a tidy mechanism story available, and we are going to leave it uninvited. Hydrogenation saturates the double bonds that distinguish one fatty acid from another, and the comedogenic-scale folklore likes to pin pore-plugging on saturated fats; the content farms duly assert that hardened oils clog more. No comedogenicity measurement of hydrogenated vegetable oil supports running that argument, in either direction, and a mechanism that would explain a result is not additional evidence for it. Separately: an industry directory calls the ingredient "safe" and notes it "may cause acne or clog pores for some individuals," but a safety profile is not a comedogenicity finding and an uncited caution is not a measurement. The one number this page can stand on is Fulton's 3, with all the caveats above attached to it.
Where you’ll see it
Industry ingredient directories describe hydrogenated vegetable oil as an emollient and structuring wax, and list the product categories it is supplied for: lip balms and lipsticks, body lotions and moisturising creams, hair conditioners, and sunscreens, as well as synthetic "beeswax" and "butter" blends, where it appears alongside other hardened waxes rather than on its own. Those are directory-attributed categories, not a measured prevalence — we have not audited the market. On a label it reads simply as Hydrogenated Vegetable Oil, and because it functions as both an emollient and a structuring wax it can sit high or low in an ingredient list depending on the product — its position there tells a reader very little about how much is present.
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, applied to the inner ear of New Zealand albino rabbits, three rabbits per assay, follicles scored for keratosis on a 0–5 scale. Read off a render of the journal scan, not off a list quoting it. Its Table I, section VI "Oils," prints "Hydrogenated vegetable oil" at 3 — a bare 3, with no parenthetical refined-grade figure of the kind it prints for avocado 3(2), olive 2(1) and almond 2(1). It also supplies the grade key the charts omit — 0 to 1 "is not considered significant," 2 to 3 is "borderline," 4 to 5 is "considered positive" — and the section footnote on every oil and butter row: "Results depend on source of raw material." It records no supplier, source oil or degree of hydrogenation for the sample tested. Fulton called the survey "not at all definitive."
- 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 second major rabbit-ear assay, from a different laboratory six years earlier, on the same 0–5 scale — cited here for what it does NOT contain. Thirty-two materials: three rabbits, ear canal, undiluted unless stated, 14 applications, microscopic grading only. Its nine vegetable oils are olive, avocado, castor, corn, sesame, safflower, peach kernel, grape seed and sweet almond; hydrogenated vegetable oil is not one of them. It is not a deferential republication of Fulton — the same paper flatly contradicts him on sodium lauryl sulfate and prints the disagreement — which is why its silence here is meaningful: the one corpus that could have given hydrogenated vegetable oil a second, independent reading simply never tested it.
- 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 paper, on the same 0–5 scale but a different key — "1 to 2 not significant, 3 or above considered positive" — and a different protocol: two rabbits per test, one ear dosed daily for two weeks with the alternate ear as control. We hold its Table I in full and cite it here for an absence: it prints no hydrogenated vegetable oil row. The 1989 grade therefore has no second Fulton reading behind it, and the shift in grade keys between his two papers is a reminder that a 3 does not mean the same thing in both.
- Nguyen SH, Dang TP, Maibach HI. "Comedogenicity in rabbit: some cosmetic ingredients/vehicles." Cutan Ocul Toxicol 26(4):287–292 (2007) The most recent rabbit-ear assay in our corpus, on a 0-to-4 scale; abstract read via EuropePMC, full text not read, so no number is carried from it. Cited only for what its fourteen named test materials do NOT include: no hydrogenated oil of any kind. It neither confirms nor contradicts the 3.
- SpecialChem INCI Directory — "Hydrogenated Vegetable Oil" An industry ingredient directory monograph, not a comedogenicity source and not a peer-reviewed document. Cited only for identity and formulation facts we could read directly: the INCI name and CAS/EINECS numbers, the physical description (a white-to-pale-yellow waxy solid, melting 32–46 °C, insoluble in water — vendor specifications for commercial grades rather than constants of a defined substance), the cosmetic functions (emollient, skin-conditioning, thickening), the product categories it appears in, and the manufacturing note that the source oil varies (coconut, palm, soybean) and that partial hydrogenation leaves trans fats. Its "safety profile" paragraph is generic vendor copy — it calls the ingredient safe and adds that it "may cause acne or clog pores for some individuals" — and carries no data, no citation and no comedone count, so we use none of it as evidence about pores.
- "Comedogenicity in cosmeceuticals: a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) A 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 surveys includes his. It finds that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. Cited for the field-wide caveat, not for anything specific to hydrogenated vegetable oil, which it does not single out. The journal is new enough that we could not retrieve a volume and page range or a full author list for it.
- Banish "Ultimate Guide to Acne-Causing Ingredients" The source recorded against hydrogenated vegetable oil in our own ratings file, and the kind of page a reader is likeliest to have met a comedogenic number on. It is a consumer-facing brand list, not a measurement, and it prints a bare number with neither Fulton's grade key nor the source-of-raw-material caveat, so the score arrives looking more settled than the one rabbit assay behind it is. We did not trace which chart it copied its figure from.
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 2026-08-05 · How we decide