Methylparaben
Methylparaben is rated Clear, and unusually for a 0 it is a measured one: Fulton's 1989 rabbit-ear assay scored a row printed under this material's own name 0 of 5, the bottom of the scale. Most of the zeros in circulation are inferences; this one is a reading. The fear attached to parabens is about other things entirely, and this page is only about pores.
Common preservative; no comedogenic concern on record.
What it is
Methylparaben is the methyl ester of para-hydroxybenzoic acid — methyl 4-hydroxybenzoate, C8H8O3, CAS 99-76-3. It is the most widely used member of the parabens, a family of preservatives that keep water-containing cosmetics from spoiling with bacteria, mould and yeast. The Cosmetic Ingredient Review's paraben assessments list its cosmetic function as preservative, and that is the whole of what a formulator reaches for it to do: it is effective at low concentrations against a broad range of microbes, stable across the pH range of most skincare, and usually paired with a longer-chain paraben such as propylparaben or with another preservative. On a label it is Methylparaben. One neighbour is worth separating from it, because on a nearby page the confusion runs the other way. Fulton's table carries three paraben rows — methyl paraben, propylparaben and phenoxyethyl paraben — each scored 0. Phenoxyethanol, a different preservative, has no row of its own anywhere in the paper; the 0 that follows phenoxyethanol around the checkers is borrowed from Fulton's phenoxyethyl paraben, a different molecule. For methylparaben there is no borrowing. The row that reads 0 is methylparaben itself.
Why we rate it Clear
We rate methylparaben Clear at Low confidence. The evidence is a single legacy rabbit-ear assay, which is what the Low records; the Clear is that the assay returned one exact result, a 0, and we identified neither confirmation nor contradiction of it anywhere else in the corpus. Silence around a number is not agreement with it, and we are not going to read it that way. Fulton's 1989 survey — the source of most comedogenic numbers in circulation — tested methylparaben and scored it 0 on its 0–5 scale. We read the row off a 400dpi render of the journal scan rather than from a list quoting it: "Methyl paraben 0", among the preservatives, with no asterisk and no range. Fulton's own key reads 0–1 "not considered significant", so a 0 is the floor of the scale. The method behind it is the one behind every Fulton number: the ingredient diluted to roughly 10% in propylene glycol, 1 mL applied to the inner ear of three New Zealand albino rabbits, follicles then scored for keratosis. It is a rabbit-ear reading, not a human one, and it is a single reading. What earns this row a page is not the number but the fact that it is a measurement at all. Many of the zeros the comedogenic checkers print are inferences — a low number handed to a material that does not appear in the assay corpus at all, on the reasoning that nothing suggested otherwise. Methylparaben's 0 is not that: the row names the material itself, and it landed at the bottom of the scale. What the paper does not give is a supplier, a purity or a grade for the sample, so the row establishes that a material called methyl paraben was on the bench, not which one. CosDNA and the other checkers list methylparaben at 0, and here, unusually, the number they print traces back to a document that measured the thing it names. The paraben controversy sits entirely to one side of this. Parabens are argued over for their weak estrogenic activity and, in a minority of people, for contact allergy. Those are different endpoints from pore-plugging, and this site rates only the last one. On the comedogenic question — the only one we answer — the row that names this material came back 0.
What the evidence doesn’t tell you
A single rabbit-ear assay from 1989 is thin evidence, and the thinness runs in every direction that the assay always does. Three rabbits, one species, and an inner-ear model Fulton warned was so sensitive that not everything which irritates it will irritate human skin. Of the survey itself he wrote that it "is not at all definitive but simply designed to stimulate research" — a judgement about the paper rather than about this one row. A 0 in that model is the absence of an effect in three rabbits at one concentration; it is not a controlled human result, and we identified no human comedogenicity study of methylparaben. Outside Fulton 1989, we identified no other comedogenicity assay of methylparaben. Morris and Kwan's 1983 rabbit-ear study — an independent laboratory, and the one legacy paper that openly contradicts Fulton on other materials — tested 32 substances, none of them a paraben. Fulton's own earlier 1984 survey carries no paraben row, and no paraben appears among the materials Nguyen, Dang and Maibach tested in 2007. Those are verified absences, checked in each paper rather than assumed. So the 0 has no independent corroboration: it is one measurement, not two that agree. An absence of contrary evidence is not the same as evidence, and a rabbit ear is not a face; both caveats apply here as they apply everywhere on this site. And the 0 speaks only to pores. It says nothing about the questions parabens are actually argued over — endocrine activity, sensitisation — which this page does not assess and which the comedogenicity assay never measured. Reading a pore result as a verdict on those questions would be the same category error the rest of this site exists to catch, run in reverse. A 2025 review of the field reports that no standardised comedogenicity test exists and that "non-comedogenic" is an unregulated label; that ceiling sits over this page too.
Where you’ll see it
On a label it appears as Methylparaben, and usually low on the ingredient list, because a preservative does its job in fractions of a percent. The Cosmetic Ingredient Review's paraben assessments describe it as one of the most widely used cosmetic preservatives, across creams, lotions, makeup and rinse-off products, most often alongside propylparaben. Its position low on a label is a fact about how preservatives are dosed, not a comedogenic signal — and there is a measured number here in any case, and it is 0.
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 rabbit-ear survey most circulating comedogenic numbers descend from, read here off a 400dpi render of the journal scan rather than through a list quoting it. Method: ingredient diluted to roughly 10% in propylene glycol, 1 mL to the inner ear of three New Zealand albino rabbits, 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". Cited as the primary and direct evidence for this rating: Table I prints "Methyl paraben 0" — the actual molecule, not a neighbour or derivative — with no asterisk and no range. Fulton called the survey "not at all definitive"; it is a single reading in one animal model, and it is the whole of the measured evidence here.
- 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 assay on the same 0–5 scale, predating Fulton 1989 and contradicting it in print on several materials — which is why it is not simply a republisher of him. Its 32 test materials were seven lanolins, nine vegetable oils, eleven esters and five surfactants. Cited for a bounded absence: no paraben is among them, so it offers methylparaben's 0 no independent corroboration in either direction.
- 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 here only for an absence: its table carries no paraben row, so it adds no second reading of methylparaben in either direction.
- 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 no paraben is among them. Cited for that absence only.
- Cosmetic Ingredient Review Expert Panel. "Final Amended Report on the Safety Assessment of Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben as Used in Cosmetic Products." Int J Toxicol 27(Suppl 4):1–82 (2008) The industry expert-panel SAFETY dossier for methylparaben, in its final published state. Cited only for identity and use — its function as a preservative, and its standing as one of the most widely used cosmetic preservatives. It assesses safety, sensitisation and systemic exposure, not comedogenicity; it measures pores nowhere, and a safety conclusion is not evidence of noncomedogenicity in either direction.
- Consumer comedogenic checkers (CosDNA and similar) Aggregators that publish a 0–5 "acne"/comedogenic number per ingredient with no disclosed method or citation. CosDNA lists methylparaben at acne 0. Cited here for a specific and unusual reason: the number these checkers print for methylparaben happens to match the one document that actually measured it (Fulton's 0). That is not corroboration — it is the same 1989 reading, quoted downstream — but it is the rare case where a checker's zero and a measured zero coincide.
- "Comedogenicity in cosmeceuticals: a review of clinical relevance, regulatory gaps, and future directions." JAAD Reviews (2025) A recent peer-reviewed review of the comedogenicity field from 1972 onward. 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