Zinc Oxide
Zinc oxide is rated Clear. For once the number the ingredient charts print — a 1 of 5 — is not wrong: it is what Fulton's 1989 rabbit assay actually records. What the charts leave out is his own key, under which a 1 "is not considered significant." So the score is a non-finding, not a measured zero and not a concern, and the belief that mineral sunscreens break you out because of the zinc oxide is not something the evidence we hold supports.
Mineral UV filter / soothing agent; low clog risk.
What it is
Zinc oxide is an inorganic compound, ZnO — an insoluble white mineral powder. It does three jobs in cosmetics, and it is worth separating them because they put it in very different products. It is a mineral (or "physical") UV filter: the US Food and Drug Administration's operative over-the-counter sunscreen order, M020, permits zinc oxide as an active at up to 25%, and permits a range of other actives besides. The familiar line about how few actives are recognised as safe and effective belongs to a separate FDA proposal from 2021 rather than to the operative order, so we do not carry it. It is a white pigment and opacifier, which is why it turns up in foundations, tinted moisturisers and powders. And it is a skin-protectant and soothing agent, which is what it is doing in calamine lotion, nappy-rash creams and after-sun balms. One neighbour is worth keeping separate from it, because the names are close and the materials are not. Zinc stearate is the zinc soap of stearic acid — a different compound, used as a powder lubricant, and Fulton scored it separately. Zinc oxide is the mineral. On a label it reads Zinc Oxide, sometimes followed by "(nano)".
Why we rate it Clear
We rate it Clear, at Low confidence, and the confidence is low because the only comedogenicity evidence for the pigment itself is a single legacy rabbit-ear grade. Start with what makes this page unusual. On most of the ingredients this site rewrites, the number in circulation is wrong — attached to the wrong molecule, or traceable to no measurement at all. Zinc oxide is not one of those. CosDNA and the acne-clinic lists give it a 1, sometimes 0–1, and that is exactly what Fulton's 1989 table prints. We rendered Table I off the journal scan and read it by eye: "Zinc oxide — 1", in the paper's miscellaneous section alongside the pigments, the mineral sunscreens and the stearates, not in the asterisked "Oils" section that carries his source-variability caveat. The number is real. What the lists drop is the key. Fulton published his own thresholds, and almost nobody quotes them: "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 1 of 5 sits in the band he himself called not significant. It is a non-finding — his assay did not see a meaningful effect — and that is a different statement from a measured zero. It is also a long way from the 4s and 5s the same table gives isopropyl myristate or laureth-4. The only human dataset we found that touches zinc oxide is about formulas, not the pigment. Draelos and DiNardo, in 2006, counted comedones on human backs before and after applying finished products — face powders, sunscreens, creams — and found that products built from ingredients the rabbit assay had flagged were frequently not comedogenic themselves. One of the products they tested was a face powder reported as more than half zinc oxide, and it came back non-comedogenic. That is evidence about a formula, not about the isolated mineral, and we are not going to convert one into the other: a product being clear tells you about the product.
What the evidence doesn’t tell you
Everything specific to zinc oxide here rests on one three-rabbit experiment from one laboratory. Fulton's method was roughly 10% of the material in propylene glycol, applied to the inner ear of three New Zealand albino rabbits, five days a week for two weeks, with follicles then scored for keratosis. That is not a human face and not a finished sunscreen, and the concentration does not match the products people ask about: he tested at roughly 10%, while sunscreens carry zinc oxide up to 25%. He established no dose-response for the row, so his 1 says nothing about what a higher concentration would have scored. And the rabbit-ear assay itself has been contested for decades: Draelos and DiNardo's 2006 re-evaluation found isolated ingredient scores a poor guide to what a product does on human skin, and a 2025 review in JAAD Reviews found that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. Those objections apply to a 1 exactly as much as to a 4. We identified no human comedogenicity study of zinc oxide on its own. So the honest statement is bounded: we have one legacy rabbit grade in the non-significant band, and one human study of finished products that happened to include a majority-zinc-oxide powder. That is the whole of it. Fulton also did not record which zinc oxide he tested: no particle size, no nano status, no surface coating, no dispersion medium. Cosmetic zinc oxide is sold across all of those, and one unspecified sample cannot stand in for the range. Nor is there a second reading to set beside his — zinc oxide has no row in Fulton's 1984 paper, none in Morris and Kwan 1983, and none in Nguyen 2007. Those are absences we checked in the papers themselves, not zeros. A non-finding is not a disproof, and we would rather say so than let a low number read as a guarantee. Fulton's 1 means his assay did not see an effect; it does not establish that zinc oxide can never contribute to a clogged pore in any person or any product. People do break out from mineral sunscreens, and the evidence we hold identifies no cause for it. Draelos and DiNardo tested one majority-zinc-oxide powder and found it non-comedogenic; that is a fact about that powder, not a verdict on the pigment and not a verdict on the rest of anyone's formula. It is also commonly said that zinc oxide stays on the skin's surface and therefore cannot enter a follicle. That is a reasonable expectation for an insoluble mineral, but it is an argument from chemistry, not a comedone count, and we are not going to present it as evidence. One document we could not lean on, noted so you know we looked: the Cosmetic Ingredient Review's 2024 safety assessment of zinc salts explicitly excludes zinc oxide — the panel judged its zinc–oxygen bond too covalent to group with the salts — so we found no CIR review of this exact material, and a safety review would not be a comedogenicity result in any case.
Where you’ll see it
Mineral or "physical" sunscreens, where it is an active ingredient at up to 25% in the United States. Tinted moisturisers, BB creams, foundations and pressed or loose powders, where it works as a white pigment and opacifier. And the soothing, protectant products — calamine lotion, nappy-rash and diaper creams, after-sun balms — where it has been used for a very long time. On a label it is Zinc Oxide, occasionally marked "(nano)". Do not read it as Zinc Stearate, which is a different material with its own 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, and the origin of the 1 the ingredient charts print for zinc oxide. Read off a 400dpi render of the journal scan rather than via a list quoting it. Method: 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 under a micrometer. Table I prints "Zinc oxide — 1" in the miscellaneous section (pigments, mineral sunscreens, stearates), NOT in the asterisked "Oils" section, so the source-variability footnote does not attach. By Fulton's own published key, "a minimal grade of 0 to 1 is not considered significant" — so this is a non-finding, not a positive result. Zinc stearate is a separate row at 0.
- 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, cited here for what it establishes and no more: it tested FINISHED PRODUCTS — face powders, sunscreens, creams — on small human back panels by cyanoacrylate follicular biopsy, counting comedones before and after and calling a product non-comedogenic when the increase stayed under 50%, and it concluded that products built from comedogenic-rated ingredients are frequently not comedogenic themselves, with mineral pigments generally testing clear. It does not report a per-ingredient comedogenic score for zinc oxide, and we do not cite it for one. Its relevance is the finished-formula caveat: one of its test articles was a face powder reported as majority zinc oxide, and it tested non-comedogenic — evidence about a formula, not the isolated pigment.
- US Food and Drug Administration. Over-the-Counter Monograph M020, "Sunscreen Drug Products for Over-the-Counter Human Use" (2021) The deemed final order governing over-the-counter sunscreens in the United States. Cited only for what zinc oxide IS and how it is used: the order permits zinc oxide as a sunscreen active at up to 25%, alongside a range of other permitted actives. The familiar line about how few actives are recognised as safe and effective belongs to a separate FDA PROPOSED order from 2021, not to this operative one, and we do not rely on it. Either way this is a regulatory classification, not a comedogenicity assessment, and it says nothing 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. Finds that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label. A synthesis of the legacy literature rather than a new measurement, independent of Fulton only in authorship; cited for the field-wide caveat that applies to a low score as much as a high one.
Others in the same family
Minerals & pigments 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 minerals & pigments as a family ›
Last reviewed 2026-08-12 · How we decide