Porecelain

Flawless skin starts with the fine print.

Allantoin

Most pages on this site exist because a comedogenic number was attached to the wrong material. This is not one of them. Fulton's 1989 table really does print a row for allantoin, the grade really is 0 on his 0-to-5 scale, and the number belongs to the molecule it is quoted against. What sits behind it is one reading, in one rabbit assay, in one paper — and the safety review that covers 1,376 products does not take the question up anywhere in the text we searched.

Clear Low confidence Legacy score 0 on a 0-5 scale · Fulton 1989 · low reliability

Fulton 1989 rabbit ear 0 of 5; no second assay we can find.

What it is

Allantoin is a small heterocyclic organic compound, CAS 97-59-6. The Cosmetic Ingredient Review's 2010 assessment, working from the International Cosmetic Ingredient Dictionary, lists its cosmetic functions as skin-conditioning agent — miscellaneous, and skin protectant, and records something worth knowing before anything else on this page: "Its source in cosmetics is synthetic." The Panel elsewhere describes allantoin as a natural metabolic product, which it is; the material in the bottle is made, not extracted. We file it under botanicals on this site. That is a shelving decision, not a claim about where it comes from. Its other names matter here more than they usually would, because one of them is a near-miss for a different ingredient. CIR lists allantoin as (2,5-dioxo-4-imidazolidinyl)urea, glyoxyldiureide, ureidohydantoin and 5-ureidohydantoin, among others. It is, chemically, a hydantoin derivative. Hold on to that. It is water-loving and not oily. The supplier data CIR reproduces describes allantoin as soluble in hot water, slightly soluble in cold water, glycerin and propylene glycol, very slightly soluble in alcohol, and practically insoluble in apolar solvents including mineral oil. FDA's over-the-counter skin protectant monograph, 21 CFR 347.10, lists allantoin as an active ingredient at 0.5 to 2 percent.

Why we rate it Clear

We rate allantoin Clear at Low confidence, and the confidence is the part to read. The evidence behind it is one line in one table, and that is the whole of what we could trace. The number, and it is the right one. James Fulton's 1989 survey in the Journal of the Society of Cosmetic Chemists is the paper nearly every comedogenic score in circulation descends from, and we read its Table I off a 400dpi render of the journal scan rather than off a list quoting it. It prints a row reading "Allantoin" at a comedogenicity grade of 0 on his 0-to-5 scale. No range, no asterisk. It sits outside the asterisked oils section, whose footnote — "results depend on source of raw material" — governs every oil and butter row in the paper and does not reach this one. The row is the material. Nothing has been substituted, promoted from a neighbour, or read off a similar-looking name. What the row does not carry is any account of the material itself: Fulton reports no supplier, no purity, no grade and no batch, so the match holds at the level of the name and no further. That sentence is rarer on this site than it should be, which is why it is the finding rather than the throat-clearing. Coconut oil's famous 4 is coconut butter's. The high score quoted against wheat germ oil belongs to wheat germ glyceride, which the table prints at 3. Allantoin's 0 is allantoin's. What Fulton's own key says a 0 is worth. He published one: "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." A 0 is the floor of the band he treated as noise rather than as a finding. He also described the survey as "not at all definitive but simply designed to stimulate research." And it is one reading. Fulton's earlier survey with Pay and Fulton, 1984, in the Journal of the American Academy of Dermatology — a print copy of which we hold and have transcribed in full — has no allantoin row. Morris and Kwan's 1983 table in the same journal as the 1989 paper runs to 32 rows: seven lanolins, nine vegetable oils, eleven esters, five surfactants. No allantoin. The abstract of Nguyen, Dang and Maibach's 2007 rabbit study names the fourteen materials it tested, and allantoin is not among them. The document you would expect to settle it does not address it. CIR's Final Report on allantoin and its related complexes — Becker and colleagues, International Journal of Toxicology, 2010, covering an ingredient reported in 1,376 cosmetic products — runs to fourteen journal pages of chemistry, toxicology, irritation, sensitisation, penetration and clinical use. We searched the full text of the published PDF. The words comedogenic, comedone, acne, sebum and pore do not appear in it anywhere. That is not a criticism of the report. It is a safety assessment, it reached a safety conclusion, and comedogenicity was not its question. But it means the reassurance a reader might take from "CIR says allantoin is safe" is reassurance about something else. So: one rabbit reading, from 1989, on a scale whose author called a 0 insignificant, and no second measurement of any kind that we could find.

What the evidence doesn’t tell you

We identified no human comedogenicity study of allantoin — no cyanoacrylate follicular biopsy, no occluded back application, no counted comedones on a person. We also identified no case report attributing comedones or an acneiform eruption to it. A 0 from the rabbit ear is as weak as a 4 from it. The method is roughly 10% of the ingredient in propylene glycol, applied to the inner ear of three New Zealand albino rabbits, five days a week for two weeks, follicular keratosis then graded under a micrometer. This site discounts that model when it condemns an oil; consistency requires discounting it here. One reading from a weak, oversensitive model is weak evidence, whichever direction it points. There is a specific problem with the vehicle, and we are going to state it as a question rather than as a finding. Fulton's method dissolved test materials at roughly 10% in propylene glycol. The supplier data CIR reproduces describes allantoin as only slightly soluble in propylene glycol. Neither document reports whether the material was in solution or in suspension at that concentration, and Fulton reports no solubility data, no certificate of analysis and no observation of what happened in the vehicle. We are not claiming that nothing reached the follicle. We are saying that the paper names the test article, the vehicle and the nominal concentration but not the physical state of the material on the ear — dissolved, suspended, or crystallised out — and that this is a real gap in a reassuring result rather than a technicality. There is no dose series. CIR's use tables record allantoin in cosmetics at 0.0001% to 2%, and the skin-protectant monograph range runs to 2 percent. The Panel noted, against itself, that none of the sensitisation and irritation studies it reviewed were conducted at the 2% level actually reported in cosmetics. That observation is about irritation testing, not about pores. On comedogenicity there is no concentration to compare against: one grade, at one concentration, in one animal model. Something was measured on human skin, and it was not this. CIR reports penetration of human skin by allantoin at 1%: 5.00% ± 1.25% at three hours and 6.9% ± 1.4% at six hours from a hydrophilic gel, with higher figures from an oil-in-water cream and a water-in-oil ointment. Penetration is not follicular plugging. That work counted no comedones and examined no follicles, and it is evidence about neither the rating nor its opposite. A name to watch, and a limit on what we will say about it. Fulton's table prints a row labelled "Hydantoin" immediately below the allantoin row, and in our render of the scan its grade column is blank. Banish's widely circulated comedogenic chart, in its April 2026 revision, prints "Hydantoin (0)" in its low-risk column. We have not traced where that 0 came from, and we are not going to assert that it was read off a blank cell in this table. What we will say is that allantoin and hydantoin are two rows, that one of them has no printed grade in the copy we read, and that DMDM hydantoin — a different cosmetic ingredient again — is not what either row is about. CIR's 2010 report covers allantoin and six named complexes: allantoin ascorbate, biotin, galacturonic acid, glycyrrhetinic acid, panthenol and polygalacturonic acid. It is not an assessment of every ingredient with "allantoin" in its name, and nothing on this page should be read across to one. Finally, a rating belongs to an ingredient, not to a product. The 0 here belongs to the humectant-like conditioning agent, at whatever concentration a formulator used, in a rabbit's ear, in 1989.

Where you’ll see it

Soothing and barrier-repair positioning, mostly: post-procedure and after-sun products, baby and nappy-rash preparations, hand and body creams, lip products, and cleansers and toners aimed at sensitive skin. The only use figures we will quote are CIR's, and they are a decade and a half old. As of the 2010 report, industry reported allantoin to the FDA's Voluntary Cosmetic Ingredient Reporting Program in 1,376 cosmetic products, and a CTFA concentration survey put its use range at 0.0001% to 2%. The report records eleven sprays and fixatives, and gives examples at 0.2% in an eye pencil, an eye cream, skin wipes and a skin toner. A registration count and an industry survey from around 2010 are not a current market survey, and a maximum reported use level is a formulation figure, not a demonstration of tolerance across that range. Separately from cosmetics, FDA's over-the-counter skin protectant monograph, 21 CFR 347.10, lists allantoin as an active ingredient at 0.5 to 2 percent, which is why it also turns up on drug facts panels rather than only in ingredient lists.

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 nearly every comedogenic number in circulation descends from, read here off a 400dpi render of the journal scan rather than off a list quoting it. Method: ingredient at roughly 10% in propylene glycol, 1 ml to the inner ear of three New Zealand albino rabbits, five days a week for two weeks, follicular keratosis graded under a micrometer on a 0-to-5 scale. Its Table I prints a row for "Allantoin" at 0, with no range and no asterisk, outside the asterisked oils section — and a row labelled "Hydantoin" immediately below it whose grade column is blank in our render. Fulton's own key: 0 to 1 "is not considered significant." He called the survey "not at all definitive but simply designed to stimulate research." Cited as the single traceable comedogenicity datum for this ingredient, and as the same contested assay this site discounts elsewhere: a reassuring 0 from it is as weak as a condemning 4.
  2. Becker LC, Bergfeld WF, Belsito DV, Klaassen CD, Marks JG Jr, Shank RC, Slaga TJ, Snyder PW, Andersen FA. "Final Report of the Safety Assessment of Allantoin and Its Related Complexes." Int J Toxicol 29(Suppl 2):84S-97S (2010); doi:10.1177/1091581810362805 A Cosmetic Ingredient Review expert-panel SAFETY assessment of allantoin and six named complexes. Document state is clean and is the published Final Report, not a draft or tentative packet. Cited for four things and no more. One: the identity data — CAS 97-59-6, the synonym 5-ureidohydantoin, the functions skin-conditioning agent and skin protectant, and the statement that "its source in cosmetics is synthetic." Two: the physical data reproduced from a supplier data sheet, including that allantoin is only slightly soluble in propylene glycol and practically insoluble in mineral oil. Three: the use data — 1,376 products in the FDA's VCRP and a CTFA-surveyed range of 0.0001% to 2%. Four: the human penetration figures for allantoin at 1%. It is cited AGAINST an easy reading as well: we searched the full text of the published PDF and the words comedogenic, comedone, acne, sebum and pore do not appear in it. A safety conclusion is not a comedogenicity finding, and this report does not contain one.
  3. US Food and Drug Administration. "Skin protectant active ingredients," 21 CFR 347.10, in Skin Protectant Drug Products for Over-the-Counter Human Use The federal monograph that lists which actives may be sold as over-the-counter skin protectants, and at what strengths. Cited for one line and nothing else: allantoin at 0.5 to 2 percent. It is quoted here directly rather than through a secondary report reproducing it, because the range is the figure on this page a reader is most likely to check. A monograph listing is a regulatory permission for a claimed use. It is not a comedogenicity finding, and no follicular measurement of any kind sits behind it.
  4. 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) The same author's earlier rabbit-ear survey, on the same 0-to-5 scale but with a different grade key, read in full from a print copy and transcribed row by row. Cited here purely for what it does not contain: its Table I has no allantoin row. That matters because this paper is the reason several other numbers on this site are contested, so its silence is a real absence rather than an untested assumption.
  5. 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, six years before Fulton 1989, which openly contradicts him on several materials. Its table runs to 32 rows — seven lanolins, nine vegetable oils, eleven esters and five surfactants — and contains no allantoin row. Cited as the second place a second number could have come from, and did not.
  6. Nguyen SH, Dang TP, Maibach HI. "Comedogenicity in rabbit: some cosmetic ingredients/vehicles." Cutan Ocul Toxicol 26(4):287-292 (2007); PMID 18058303 A later rabbit-ear study on a different scale again (0-to-4). We have read its abstract verbatim and not its full text, so no per-material number from it appears anywhere on this site. Cited for one thing only: the abstract names the materials tested — isopropyl palmitate, isopropyl myristate, butyl stearate, isopropyl isostearate, decyl oleate, isostearyl neopentanoate, isocetyl stearate, myristyl myristate, cocoa butter, cetyl alcohol, paraffin, stearyl alcohol, sodium lauryl sulfate and petrolatum — and allantoin is not among them.
  7. Banish. "The Ultimate List of Pore Clogging Ingredients To Avoid," blog article dated 7 April 2026, read 15 August 2026 A skincare retailer's blog post carrying a large comedogenic-ratings chart, and one of the places a reader will actually meet allantoin's 0. Characterised as what it is: a commercial list, not a measurement. Its chart tracks Fulton's Table I closely enough to carry his own misspelling of carnauba wax as "Carnuba wax," but it also contains rows that are not in his table, so it is not a straight reproduction of one paper and we do not describe it as one. The seven references it cites sit under its prose rather than under the chart, and no source is given for any individual rating. Cited here for two facts: it prints "Allantoin (0)," and it prints "Hydantoin (0)" for a row whose grade column is blank in our render of Fulton's table. We have not traced the second number to any source and make no claim about where it came from.

Others in the same family

Botanical extracts 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 botanical extracts as a family ›

Last reviewed 2026-08-20 · How we decide

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