Glyceryl Stearate
Glyceryl stearate is rated Clear: it is the plain, non-self-emulsifying emulsifier that Fulton's 1989 rabbit-ear assay scored 1 on its 0–5 scale, a number he filed as not significant — and the higher 3 that sometimes follows the name is a different material, the self-emulsifying "SE" grade, which has soap blended into it and its own entry on this site.
Very common emulsifier; the plain (non-SE) form is widely considered non-comedogenic.
What it is
An emulsifier — the ingredient that keeps the oil and water phases of a cream from separating. Glyceryl stearate names an ester of glycerin and stearic acid, though the commercial material is a mixture rather than a single compound: mono-, di- and triesters together, with a distribution of fatty-acid homologues alongside the stearate, in proportions that vary with the grade and the supplier. Fulton recorded no composition and no supplier for the sample he tested. On its own it is a weak, "non-self-emulsifying" emulsifier that usually needs a co-emulsifier to build a stable lotion. On a label it is Glyceryl Stearate, and it is one of the most common emulsifiers in cosmetics: the Cosmetic Ingredient Review's frequency-of-use data records over 5,000 reported uses. There is a second, separately named grade that matters here because the legacy literature scored it differently. "Glyceryl Stearate SE" is a distinct, self-emulsifying commercial grade of glyceryl stearate with a small amount of sodium and/or potassium stearate — soap — blended in, which lets it emulsify a cream more readily on its own. It is a different INCI name and a separate entry on this site. The label resolves which of the two grade names a product uses, and so which legacy row is the one to read; it does not establish that the ester in the jar is the ester Fulton put on the rabbit.
Why we rate it Clear
We rate it Clear, at Low confidence, and the confidence is Low because the only comedogenicity evidence we identified is two rabbit-ear assays from the 1980s. The primary number is James Fulton's 1989 survey, the source of most comedogenic scores in circulation. His table prints two distinct rows for this ingredient, and they do not agree: "Glyceryl stearate NSE" — the non-self-emulsifying plain grade, plausibly the material a label calls simply "Glyceryl Stearate", though that mapping is a name-level crosswalk rather than a printed match, since no row prints the unqualified name — scores 1, and "Glyceryl stearate SE" scores 3. Both are on his 0–5 scale. The method behind the numbers is the one behind almost every score of this kind: the ingredient diluted to roughly 10% in propylene glycol, applied to the inner ear of a New Zealand albino rabbit, three rabbits per assay, five days a week for two weeks, the follicular keratosis read under a micrometer. Fulton's own key to his scale is the part almost nobody quotes, and it settles what the plain grade's number is worth. In his words: "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." By that key the plain grade's 1 is not significant. The 3 that sometimes travels with the name "glyceryl stearate" is the SE grade's — and even that 3 is the top of Fulton's borderline band, not a positive finding. So the material identity is the whole page: Fulton's row for the plain grade is printed under the qualified name "Glyceryl stearate NSE", it is a 1, reading it across to the unqualified modern name is a crosswalk we make and say we make, and the higher number belongs to the soap-containing SE grade, which is a different ingredient with its own INCI name and its own entry. One genuinely independent measurement exists, which is rare on this site. Morris and Kwan, in 1983 — six years before Fulton, in a different laboratory — tested glyceryl stearate at 50% in mineral oil and scored it 2 of 5. That is the whole of what we can say about it, and deliberately so: we do not hold Morris and Kwan's own key to their scale, so their 2 gets its number, its concentration and its paper, and no band label borrowed from Fulton or anyone else. It is a real non-Fulton reading. It does not resolve the grade question, because Morris and Kwan recorded the material only as "Glyceryl Stearate," with no SE or NSE designation, and it cannot tell you whether the soap in the SE grade is what moved Fulton's number from 1 to 3. On that last point we stop where the data stops. Fulton printed a 1 for the plain grade and a 3 for the SE grade, and the chemical difference between them is the added stearate soap, so it is tempting to conclude the soap is the cause. Fulton offered no mechanism for the two rows, and we have found no study that isolates the soap's contribution. The honest statement is that the self-emulsifying grade scored higher than the plain grade in one 1989 assay, and that the reason is not established.
What the evidence doesn’t tell you
The direct evidence we identified is two rabbit-ear studies. The rabbit-ear assay has been questioned in the dermatology literature for decades: Draelos and DiNardo's 2006 paper in the Journal of the American Academy of Dermatology found that its results do not reliably transfer to human skin, and a 2025 review in JAAD Reviews concluded that no standardised comedogenicity test exists at all and that "non-comedogenic" is an unregulated label. Those are the reasons this rating carries Low confidence rather than more. The score is also a score for a fixed test condition, not for a product. Fulton applied the ingredient at roughly 10% in propylene glycol; Morris and Kwan applied it at 50% in mineral oil. We hold no measured in-use concentration for glyceryl stearate in any finished product, and a formula's other ingredients, pH and structure all change how any single component behaves. A rabbit-ear grade is not a dose–response curve, and it is not a prediction about a specific lotion. We identified no human comedogenicity study of glyceryl stearate in either grade. Nor does the rest of the legacy corpus add a third reading, and we checked rather than assumed: Fulton, Pay and Fulton's earlier 1984 survey carries no glyceryl stearate row, and the ingredient is not among the materials Nguyen, Dang and Maibach tested in 2007. Those are verified absences, not zeros. The Cosmetic Ingredient Review has assessed the ingredient and concluded it is safe for topical use, but that assessment is about safety, not pores: the words comedogenic, comedone, acne and follicle do not appear in its review of this ingredient. A clean safety record is not evidence either way about clogging. Finally, the grade ambiguity cuts both ways. Popular comedogenic charts often print a single number for "glyceryl stearate" without stating a grade, and Morris and Kwan did not record theirs, so the number a reader meets may belong to the plain grade, the SE grade, or an unstated one. The 1 on this page belongs to the material Fulton labelled "NSE," the plain grade a label names "Glyceryl Stearate." Whether a given jar's ester matches his is not knowable from an ingredient list.
Where you’ll see it
In oil-in-water creams and lotions, where it does the ordinary work of holding an emulsion together — moisturisers, sunscreens, cleansing milks, hair conditioners. It is one of the most common emulsifiers in cosmetics; the CIR's frequency-of-use data records over 5,000 reported uses. Those are categories, not a measured prevalence in any one product type, and label position is not a dose. The one thing worth checking on the label is the name. "Glyceryl Stearate" and "Glyceryl Stearate SE" are different INCI names with different legacy scores — 1 and 3 in Fulton's table — and only the plain name carries this page's Clear. If a label reads "Glyceryl Stearate SE," the number that applies is the SE grade's, and that ingredient has its own separate entry.
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, read off our verbatim transcription of Table I rather than via a list quoting it. A rabbit-ear assay: the ingredient diluted to roughly 10% in propylene glycol, 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, graded 0–5. It prints two separate rows for this ingredient — "Glyceryl stearate NSE" at 1 and "Glyceryl stearate SE" at 3 — which is the reason grade decides the number on this page. Fulton's own key files 0–1 as "not considered significant," 2–3 as "borderline" and 4–5 as "considered positive," and he called the survey "not at all definitive but simply designed to stimulate research." Not a measurement of a finished product, and not human data.
- 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) A genuinely independent rabbit-ear assay — a different laboratory, six years before Fulton, and one that openly contradicts Fulton on other materials in print. It scored glyceryl stearate 2 of 5, tested at 50% in mineral oil. We do not hold this paper's own key to its scale, so that 2 is reported here with its scale, its concentration and its paper attached, and with no band label borrowed from another author. Cited as a real second measurement, with its limit stated: it records the material only as "Glyceryl Stearate," with no SE or NSE designation, so it cannot adjudicate the difference between the two grades. Read from our transcription of its ingredient table (its oils table is printed rotated and is lost to OCR).
- 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, on a 0–5 scale with its own key — 1–2 not significant, 3 or above considered positive — which is not the 1989 key and cannot be read with it. Cited for an absence only: its table carries no glyceryl stearate row in either grade, so it adds no third reading.
- 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-canal study on a 0–4 scale, a third scale easy to misread as Fulton's. Its abstract names its test materials and glyceryl stearate is not among them. Cited for that absence.
- Cosmetic Ingredient Review (Fiume MM, et al.). "Amended Safety Assessment of Monoglyceryl Monoesters as Used in Cosmetics." Int J Toxicol 39(1_suppl) (2020) An industry-funded but independently paneled toxicological review, the published final version of the assessment that supersedes the CIR's 1982 Final Report — which had already concluded that glyceryl stearate and glyceryl stearate SE are safe for topical application to humans. Cited here for two narrow, stable facts only: that both grades are assessed safe as used, and that glyceryl stearate is very common in the CIR's frequency-of-use data (over 5,000 reported uses). It is a safety review, not comedogenicity evidence — the words comedogenic, comedone, acne and follicle do not appear in its treatment of this ingredient, and safety and comedogenicity are different questions.
- Draelos ZD, DiNardo JC. "A re-evaluation of the comedogenicity concept." J Am Acad Dermatol 54:507–512 (2006) A Current Issues and Opinion piece in JAAD that tested finished products on human upper backs and found products testing non-comedogenic despite containing ingredients the rabbit assay had graded as comedogenic. Cited against this rating as much as for it: it is part of why the confidence here stays Low. It is evidence that a single ingredient's rabbit-ear grade does not transfer to the formula it ends up in; it is not a head-to-head validation of the rabbit ear against human skin.
- "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 literature from 1972 to 2025. Finds that no standardised comedogenicity test exists and that the "non-comedogenic" label is unregulated. 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 sits under every legacy score on this site.
Others in the same family
Emulsifiers 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 emulsifiers as a family ›
Last reviewed 2026-08-12 · How we decide