Porecelain

Flawless skin starts with the fine print.

Caprylyl Glycol

Caprylyl glycol rates Clear, but the rating is a judgement rather than a reading: we identified no comedogenicity assay of it in any numeric paper we hold, and the low number consumer checkers print traces to no primary assay we could find. Fulton's rabbit-ear table, the source of most circulating comedogenic numbers, has no caprylyl glycol row — it scored caprylic acid, a different molecule that happens to share the name.

Clear Low confidence No legacy score. It does not appear in the assay corpus we searched.

No assay we can find, and no comedogenic concern on record.

What it is

Caprylyl glycol is 1,2-octanediol: an eight-carbon diol, a short chain with two hydroxyl groups on adjacent carbons at one end. Its formula is C8H18O2 and its molecular weight is about 146 g/mol; its CAS number is 1117-86-8, and it is also written capryl glycol, 1,2-octylene glycol or 1,2-dihydroxyoctane. The Cosmetic Ingredient Review's 2012 assessment lists its cosmetic functions as hair conditioning agent, skin-conditioning emollient and preservative. It is a humectant with mild antimicrobial activity, and it is often paired with a conventional preservative such as phenoxyethanol; the reason usually given for that pairing is that it allows a lower dose of the main preservative, which is formulation lore we have not traced to a source. On a label it is Caprylyl Glycol. One near neighbour is not this material, and it is one untraced explanation for a number ever attaching to caprylyl glycol at all. Caprylic acid — octanoic acid — is an eight-carbon fatty acid, not a diol, and Fulton did score it. The two share the "capryl" root and the carbon count and nothing else about their structure. Capric acid, propylene glycol, butylene glycol and hexylene glycol are all separate rows in the same rabbit-ear tables, and none of them is caprylyl glycol either.

Why we rate it Clear

We rate caprylyl glycol Clear at Low confidence. Clear here is an editorial risk classification, not a measured pass, and the Low records that the direct measurement is missing entirely: we found no comedogenicity assay of caprylyl glycol in the papers we hold or the searches we ran. Start with what is absent, because it is most of the story. We identified no comedogenicity assay of caprylyl glycol in any of the numeric papers we hold. Fulton's 1989 rabbit-ear table, which we read row by row off a 400dpi render, has no caprylyl glycol, 1,2-octanediol or octylene glycol entry anywhere among its 220 rows. It does carry caprylic acid at 1 and capric acid at 2 on its 0–5 scale, along with propylene glycol at 0, butylene glycol at 1 and hexylene glycol at 0–2* — the asterisk being Fulton's "results depend on source of raw material" — and every one of those is a different molecule. Fulton, Pay and Fulton's separate 1984 rabbit-ear paper, on its own 0–5 scale (1–2 not significant, 3 or above positive), has no caprylyl glycol row either, and we have now read its Table I in full. Morris and Kwan's 1983 assay, an independent laboratory on the same 0–5 scale, tested 32 materials — seven lanolins, nine vegetable oils, eleven esters and five surfactants — and a 1,2-diol is not among them. Nguyen, Dang and Maibach's 2007 rabbit-ear study, on a 0–4 scale, names its fourteen test materials in its abstract, and caprylyl glycol is not one of them. Our index of the legacy corpus records no score for caprylyl glycol from any document in it — a statement about that corpus, not a claim about the whole literature. The gap survives even in the fullest republished lists. The Banish comedogenic database reproduces essentially all of Fulton's Table I — a couple of hundred rows, down to the individual dyes — and it has no caprylyl glycol row, while caprylic acid (1) sits right in it. So the low number some consumer checkers print for caprylyl glycol is not even inherited from the usual republished chart; where it came from, we cannot show. The near-namesake caprylic acid, one row away and scored a 1, is an obvious candidate for a mis-transcription, but we did not trace the copy and will not assert it. What caprylyl glycol has instead of an assay is a safety review. The Cosmetic Ingredient Review assessed it, together with the other 1,2-glycols, in 2012, and concluded the group safe as used on the basis of repeat-dose systemic toxicity and genotoxicity data; its 2012 use survey reports caprylyl glycol in about 2,100 formulations at 0.00003% to 5%. That is a safety conclusion, not a comedogenicity finding — the report addresses irritation, sensitisation, dermal penetration and systemic toxicity, and we identified no comedogenicity data in it. Clear rests on those things: an absence we looked for and did not fill, a safety record carrying no adverse comedogenic signal, and no measurement in either direction. Untested is not the same as safe, which is why the confidence is Low.

What the evidence doesn’t tell you

This rating is built on absence of evidence, which is a weaker thing than evidence of absence. We identified no rabbit-ear assay of caprylyl glycol, no human comedone-induction study and no follicular biopsy, in either direction. An absence of findings and an absence of looking produce the same silence, and here it appears to be the second: caprylyl glycol is not one of the fixed oils, waxes, fatty acids and esters those surveys were built around. It is an amphiphilic eight-carbon 1,2-diol — a short alkyl chain carrying two adjacent hydroxyl groups, at home in water and in oil — and structure alone does not determine comedogenicity. That is context, not a result, and reasoning of exactly that shape is how unsourced zeros get into ingredient columns. We lean on it lightly and not at all as proof. Nor can we go further than the documents we searched. An audit can establish that no assay turned up in the papers we hold and the searches we ran; it cannot establish that none was ever run anywhere, so the honest claim is bounded to what we looked at. The CIR safety review is the strongest document on this page and it measured the wrong thing for this exact question: safety, penetration and irritation are not comedogenicity, and its silence on pores is not proof that the wider literature is silent. And there is no dose–response information of any kind — there is no comedogenic number to attach to any concentration, so where caprylyl glycol sits on an ingredient list tells a reader nothing. Beyond this ingredient, a 2025 review of the field reports that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label; that ceiling applies here too.

Where you’ll see it

On a label it appears as Caprylyl Glycol, usually low in the ingredient list because it is used at low percentages. The CIR's 2012 assessment recorded it in about 2,100 cosmetic formulations at 0.00003% to 5% in the survey data of that year, across leave-on and rinse-off products, eye-area products and a handful of baby products; that is a 2012 count rather than a current one, and we hold no measured distribution within the range. It often appears next to phenoxyethanol, where the two work together as a preservative system. That it tends to sit low on the list is a fact about how it is dosed, not a comedogenicity signal — and there is no measured number to read off its position in any case.

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.

  1. Fulton JE. "Comedogenicity and irritancy of commonly used ingredients in skin care products." J Soc Cosmet Chem 40:321–333 (1989) The rabbit-ear survey most online comedogenic numbers descend from. Method: ingredient diluted to 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 whose own key reads 0–1 "not considered significant," 2–3 "borderline," 4–5 "considered positive." Read here off a 400dpi render of the journal scan rather than through a list quoting it. Cited for an absence: its 220 rows contain no caprylyl glycol, 1,2-octanediol or octylene glycol entry. They do contain caprylic acid (1), capric acid (2), propylene glycol (0), butylene glycol (1) and hexylene glycol (0–2*), each a different molecule. Fulton called the survey "not at all definitive." It supports no rating of caprylyl glycol in either direction.
  2. Fulton JE Jr, Pay SR, Fulton JE 3rd. "Comedogenicity of current therapeutic products, cosmetics, and ingredients in the rabbit ear." J Am Acad Dermatol 10(1):96–105 (1984) An earlier, separate rabbit-ear study from the same lead author: two New Zealand albino rabbits per test, one ear dosed daily for two weeks with the other as control, results on a 0–5 scale whose threshold is not the 1989 threshold (1984 reads 1–2 as not significant and 3 or above as positive), so its numbers cannot be compared with 1989 numbers without carrying each paper's own key. We have read its Table I in full. Cited here only because it contains no caprylyl glycol row and therefore adds no score.
  3. 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 laboratory's rabbit ear-canal assay on the same 0–5 scale: three rabbits, materials applied undiluted unless stated, 14 applications, graded microscopically. It predates Fulton 1989 and contradicts it in print on several materials, which is why it is not simply a republisher of him. Its 32 test materials are seven lanolins, nine vegetable oils, eleven esters and five surfactants. Cited for an absence: no 1,2-diol, and no caprylyl glycol, is among them.
  4. 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 all fourteen test materials (esters, fatty alcohols, hydrocarbons, one butter and one surfactant). Cited for a verified absence: caprylyl glycol is not one of them.
  5. Johnson W Jr, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler D, Marks JG, Shank RC, Slaga TJ, Snyder PW, Andersen FA. "Safety Assessment of 1,2-Glycols as Used in Cosmetics." Int J Toxicol 31(6 Suppl):147S–168S (2012) The industry expert-panel SAFETY dossier for caprylyl glycol and the other 1,2-glycols, in its final published state. Cited for identity and use data and for one bounded absence. It lists caprylyl glycol's functions as hair conditioning agent, skin-conditioning emollient and preservative (CAS 1117-86-8); reports it in about 2,100 formulations at 0.00003% to 5%; and concludes the 1,2-glycol group "safe in the present practices of use and concentration," on repeat-dose systemic toxicity and genotoxicity data. We identified no comedogenicity data anywhere in it. A safety conclusion is not evidence of noncomedogenicity, its use table is a 2012 survey rather than a current one, and its silence on pores is not evidence that the wider literature is silent.
  6. Banish. "The Ultimate List of Pore Clogging Ingredients to Avoid" (comedogenic ingredient database) A skincare retailer's blog that reproduces essentially the whole of Fulton's Table I as a chart — a couple of hundred rows, down to the individual D&C dyes. Not an independent measurement; it is one 1989 assay retyped. Cited for an absence within it: it has no caprylyl glycol row, while caprylic acid (1) is present — which is why the low number some checkers print for caprylyl glycol cannot be traced even to the standard republished chart.
  7. Consumer comedogenic checkers and ingredient databases (CosDNA, SkinWis and similar) Aggregators that publish a 0–5 "acne" or comedogenic number per ingredient with no disclosed method, provenance or citation. Caprylyl glycol is listed on pages of this kind at a low value, commonly 1 of 5. Cited as the artefact being corrected, not as a measurement: we traced no primary assay behind that number and make no claim about where it came from or who entered it. It is not carried as our legacy value.
  8. "Comedogenicity in cosmeceuticals: a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) A recent peer-reviewed clinical review of the comedogenicity field from 1972 onward. It is a synthesis of the same legacy literature, not a new measurement, and independent of Fulton only in authorship. Cited for one field-wide caveat: no standardised comedogenicity test exists, and "non-comedogenic" is an unregulated label. It sets the ceiling on how much any comedogenic number, present or absent, can be asked to carry.

Others in the same family

Preservatives 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 preservatives as a family ›

Last reviewed 2026-08-12 · How we decide

‹ Check a full ingredient list