Polyglyceryl-3 Diisostearate
Most pages on this site exist because a number was attached to the wrong material. This one runs the other way: Fulton's table prints this exact INCI name, unabbreviated, at 4 on a 0-5 scale, and by his own key that band is "considered positive." What we could not trace is the reassurance — the ingredient directories calling it non-comedogenic name no study at all.
Branched diisostearate emulsifier (common in balms/makeup) flagged by acne-community lists.
What it is
A water-and-oil emulsifier and emollient, and one of the most widely registered members of a very large ester family. The Cosmetic Ingredient Review defines that family plainly: each member is "a polyether comprising 2 to 20 glyceryl residues, end-capped by esterification with simple carboxylic acids, such as fatty acids." The nominal structure here is three glycerol units in a chain carrying two isostearic acid groups, CAS 66082-42-6. A commercial grade is not that one idealised molecule, though: polyglyceryl esters are made as distributions, varying in how far the glycerol chain is polymerised and how completely it is esterified, which is why the CIR defines the family as a range rather than a formula. The fatty acid matters, because it is where the published descriptions of this ingredient start to come apart. Isostearic acid is a branched eighteen-carbon acid; the IUPAC name SpecialChem prints for this ingredient, "Bis(16-methylheptadecanoate)", is that acid. The CIR report reads across to a substance it calls "1,2,3-propanetriol, homopolymer, diisooctadecanoate" — diisooctadecanoate is again the eighteen-carbon diester. Yet SpecialChem's own "Origin" line, on the same page as that IUPAC name, says the ingredient "can be derived from stearic acid," which is the straight-chain relative; and a retailer glossary we read says it is made from "isodecanoic acid," which is ten carbons and not this molecule at all. There is a second, genuinely different ingredient with a near-identical name. POLYGLYCERYL-3 DISTEARATE is the straight-chain stearate, not the branched isostearate, and it has its own CosDNA entry. The retailer glossary above treats the two as the same thing and says so in print. On a label they are two separate declarations.
Why we rate it Clogging
We rate it Clogging at Low confidence, and for once the number is not the thing that goes wrong. What the primary table prints. Fulton's 1989 survey in the Journal of the Society of Cosmetic Chemists — the 220-row table nearly every circulating comedogenic score descends from — has a row reading "Polyglyceryl-3-diisostearate — 4", on a 0-5 scale. The modern INCI name for the ingredient on this page is Polyglyceryl-3 Diisostearate. That is the same string. There is no dropped word here, no derivative standing in for a parent, no adjacent row pressed into service. We check that question first on every page because it is where these numbers usually break, and on this one it holds. What the 4 means in Fulton's own key, which is quoted far less often than the number: 0 to 1 "is not considered significant", 2 to 3 is borderline, and 4 to 5 is "considered positive." So this is one of the readings his paper treats as a real result rather than noise. The row also carries no asterisk. Asterisks in that table sit both on a section heading — section VI, "Oils", where the footnote reads that results depend on the source of the raw material — and on individual rows elsewhere, among them Anhydrous lanolin 0-1*, Stearic acid 2-3* and Jojoba oil 0-2*. This row carries none, and it is not in section VI. One wrinkle in the table, which we would rather print than leave for someone else to find. Eight rows earlier, in the same section, Fulton prints "Glyceryl-3-diisostearate — 4". That is not an INCI name. The paper supplies no identifier — no supplier, no grade, no lot, no CAS number — that would decide whether the earlier row is a distinct material, an obsolete name for this one, or the same entry printed twice. We are not going to decide it either, so the 4 on this page comes solely from the row carrying the exact name. Both rows read 4. Downstream, the Face Five clinic list carries "Glyceryl-3-Diisostearate" and "Polyglyceryl 3-Diisostearate" as two separate entries in its miscellaneous section, and "Polyglyceryl-Diisistearate" as a third entry under waxes. We are not going to tell you who copied whom — we did not trace that, and matching text is not a proven chain of custody. We can tell you that a name which is not an INCI name appears both in Fulton's table and on that list. Now the other direction, which is the part of this page worth reading. Two documents we retrieved and read in full assert the opposite, and neither cites anything. SpecialChem, a business-to-business ingredient directory used by formulators, states under "Safety Profile" that the ingredient is "Non-comedogenic and biodegradable." No study, no assay, no scale, no reference. Deascal, a skincare retailer's ingredient glossary, states that it "is rated as a 1 on a scale of 0 to 5, where 0 is totally non-comedogenic and 5 is highly comedogenic," and concludes it is "suitable for individuals prone to blemishes or acne." Again no source — and it is the same page that identifies the acid as isodecanoic and treats the distearate as an alias. We could not trace either claim to any document. That is not the same as proving no document exists, and we are not claiming it is. So the evidence here is thin on both sides, and it is thinner on the reassuring side. One rabbit-ear reading says positive. Nothing we found says otherwise with a method attached.
What the evidence doesn’t tell you
Everything above rests on one assay, in one laboratory, in 1989. Fulton's method: the ingredient at roughly 10% in propylene glycol, applied to the inner ear of three New Zealand albino rabbits, five days a week for two weeks, follicular keratosis then measured. It is not a face and it is not a finished product. Fulton described his own survey as "not at all definitive but simply designed to stimulate research," and warned that the model is sensitive enough that "not everything that irritates this model will also irritate human skin." A 4 from that assay is a 4 from that assay. We found no second reading. We identified no human comedogenicity study of this material, and it has no row in the other numeric inventories we hold — Fulton, Pay and Fulton 1984, Morris and Kwan 1983, and Nguyen 2007. That matters more than usual here, because Morris and Kwan openly contradicted Fulton in print on other materials, so an independent laboratory is not a formality on this scale. The largest safety review of this ingredient does not address the question. The Cosmetic Ingredient Review's assessment of 274 polyglyceryl fatty acid esters — Status: Final Report, released 14 November 2016, and the document in which this ingredient has the single highest number of reported uses — contains no instance of the words "comedogenic", "acne" or "follicular". We searched the full text. What it does report about skin is a different endpoint: the ingredient was not irritating to rabbit skin, and was not a sensitizer in one guinea-pig study, with a guinea-pig maximization test returning inconclusive results. It also records that the ingredient was not a penetration enhancer for the drug 5-fluorouracil in vitro, which is a permeability measurement. Irritation is not comedogenicity, sensitisation is not comedogenicity, and a permeability coefficient counts no comedones. A safety conclusion is not a pore conclusion, and we are not going to read one as the other in either direction. Concentration is unresolved. Fulton dosed at roughly 10%. The CIR reports this ingredient used at up to 39% in a leave-on lipstick formulation and at 2% in baby lotions, oils and creams. The assay sits between those two figures, and a single rabbit reading contains no dose-response curve, so it cannot tell you whether the 2% product behaves like the 39% one. And we cannot tell you what Fulton actually put on the ear. He reports no supplier, no trade name, no purity and no lot number, and the family the CIR describes spans a wide range of degrees of esterification. A commercial emulsifier sold under this INCI name today is not demonstrably the same material as the one in that 1989 row.
Where you’ll see it
Water-in-oil systems and colour cosmetics. The CIR's 2016 report gives the only usage figures we have that come from a named database: of the 274 polyglyceryl fatty acid esters it assessed, this one had the most reported uses — 371, of which 363 were in leave-on formulations and 216 were in lipsticks. Those counts come from the FDA's Voluntary Cosmetic Registration Program, which is what its name says it is: registrations companies chose to file, tallied in 2016. It is not a sales figure, not a market audit, and not current. SpecialChem's directory entry lists the ingredient's functions as emollient, emulsifying and surfactant, and groups its formulations under foundations and concealers, lipsticks and glosses, and moisturisers. One naming note, kept to what can be observed. "Glyceryl-3-diisostearate", which is not an INCI name, appears both in Fulton's table and on the Face Five clinic list, where it sits alongside Polyglyceryl 3-Diisostearate and a misspelled third entry. Whether those strings denote one material or more than one is not something either document settles.
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 document and the source of the number on this page, read off the journal scan and transcribed row by row rather than quoted from a list. A rabbit-ear survey: the test substance at roughly 10% in propylene glycol, applied to the inner ear of three New Zealand albino rabbits, five days a week for two weeks, follicles then scored for keratosis on a 0-5 scale whose key reads 0-1 "not considered significant", 2-3 borderline, 4-5 "considered positive". Its Table I prints "Polyglyceryl-3-diisostearate — 4" and, eight rows earlier in the same section, "Glyceryl-3-diisostearate — 4". It reports no supplier, grade or lot for either. Fulton called the survey "not at all definitive but simply designed to stimulate research". It is one reading, in one laboratory, in animals.
- Fiume MM, Bergfeld WF, Belsito DV, et al. "Safety Assessment of Polyglyceryl Fatty Acid Esters as Used in Cosmetics." Cosmetic Ingredient Review — Status: Final Report, released 14 November 2016 (Panel meeting 26-27 September 2016) An industry-supported expert-panel safety review of 274 ingredients, not a comedogenicity study, and cited here for three things it does and one it does not. It supplies the chemical definition of the family ("a polyether comprising 2 to 20 glyceryl residues, end-capped by esterification with simple carboxylic acids"); the usage counts, which are 2016 Voluntary Cosmetic Registration Program registrations rather than sales; and the irritation, sensitisation and penetration data, all of which measure something other than follicular plugging. What it does not contain is any comedogenicity finding: the words "comedogenic", "acne" and "follicular" do not appear in it. We read the version hosted on the FDA's own document server and verified the status line on page one — Final Report, not a draft or a comment-stage packet.
- SpecialChem — "POLYGLYCERYL-3 DIISOSTEARATE: INCI Ingredient", directory entry, last updated 17 April 2026 A commercial business-to-business ingredient directory serving formulators and suppliers, not a study and not a regulatory document. Cited as the source of an uncited claim, and read in full on 12 August 2026: under "Safety Profile" it states the ingredient is "Non-comedogenic and biodegradable", with no reference, assay, scale or author attached. Its usefulness on this page is descriptive rather than evidential — it supplies the IUPAC name, the CAS number, the declared functions and the product categories. Note that its "Origin" line says the ingredient can be derived from "stearic acid" while the IUPAC name in the same panel, Bis(16-methylheptadecanoate), is the branched isostearate.
- Deascal — "Polyglyceryl-3 Diisostearate: An In-Depth Look at Its Role in Cosmetics", ingredient glossary, article last updated 15 October 2024, author given as Ward Commerce Group A skincare retailer's ingredient glossary page, cited as an artefact rather than as evidence, and read in full on 12 August 2026. It states that the ingredient "is rated as a 1 on a scale of 0 to 5" and is therefore "suitable for individuals prone to blemishes or acne", and names no study, author, journal or assay for that figure. The same page describes the ingredient as derived from "isodecanoic acid" — a ten-carbon acid, where this molecule carries eighteen-carbon branched chains — and gives "Polyglyceryl-3 Distearate", a separate INCI name, as an alias. We cite it to show what the reassuring number is attached to, not to rely on it.
- Face Five (acne clinic, Colorado Springs, CO) — "Problematic Ingredients List", page last modified 30 August 2024 An alphabetical avoid-list published by a clinic that sells acne treatment programmes and products. No patient count, no method, no scale, no bibliography, no dates: an assertion, not a dataset, and we are not going to give it an evidence base it does not claim. It is cited here for exactly one observable fact, checked against the page itself: it carries this single material as three separate entries — "Glyceryl-3-Diisostearate" and "Polyglyceryl 3-Diisostearate" in its miscellaneous section, and "Polyglyceryl-Diisistearate" among its waxes. The first of those is not an INCI name and does appear, verbatim, in Fulton's table. That is an observation about two documents, not a demonstrated chain of copying.
- 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 assay on the same 0-5 scale, six years before Fulton's 1989 survey and in a different laboratory — one of the few documents in this literature that is genuinely not downstream of him, and one that contradicts him in print on other materials. Cited here only for what it does not contain: its 32 rows cover lanolins, vegetable oils, esters and surfactants, and none of them is this ingredient. We found no second reading of this material to set against Fulton's.
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