Porecelain

Flawless skin starts with the fine print.

Sodium Benzoate

Sodium benzoate is rated Clear, and the rating is an inference from absence rather than a reading: we identified no comedogenicity assay of it in any of the primary documents we hold, and the safety literature that does exist for it — which is unusually large — never once asks the pore question.

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

Sodium benzoate (CAS 532-32-1) is the sodium salt of benzoic acid: a benzene ring with a single carboxylate group, balanced by a sodium ion. Its formula is C7H5NaO2 and its molecular weight is about 144 g/mol. It is a broad-spectrum preservative, and the Personal Care Products Council's reference summary also lists it functioning as a fragrance ingredient and a corrosion inhibitor. One property matters more than the rest, because the rest of this page keeps returning to it: it is a pH-dependent preservative. The antimicrobial work is done not by the benzoate ion but by undissociated benzoic acid, and the salt and the acid sit in a pH-dependent equilibrium. Benzoic acid's pKa is about 4.2, so the undissociated fraction falls as the pH rises past it and is already the minority species at pH 5. In a neutral or alkaline product the preservative barely functions, which is why it is normally reserved for low-pH formulas and often paired with a second preservative. In the European Union, benzoic acid and its salts are permitted as preservatives under Annex V of the Cosmetics Regulation, at maxima expressed as the acid: 2.5% in rinse-off products, 1.7% in oral-care products, and 0.5% in leave-on products. In the United States both benzoic acid and sodium benzoate are on the FDA's list of food substances affirmed as Generally Recognized As Safe. Three near-namesakes are worth holding apart from it, because the safety documents this page relies on assess them as one group and a reader could easily merge them. BENZOIC ACID is the parent acid — the species the salt is in equilibrium with, favoured as the pH falls. BENZYL ALCOHOL is a different molecule, an alcohol rather than an acid or a salt, and a separate preservative. BENZYL BENZOATE is a different molecule again: an ester of benzyl alcohol and benzoic acid, used as a fragrance ingredient and a solvent, and restricted in fragrances for sensitisation. Nothing on this page transfers to those three. The material here is the salt.

Why we rate it Clear

We rate sodium benzoate Clear at Low confidence, and the second half of that sentence carries as much weight as the first. Begin with the primary table, because the useful thing here is what is not in it. We read all 220 rows of Fulton's 1989 Table I off a 400dpi render of the journal scan, transcribed in this repository. There is no sodium benzoate row. There is no benzoic acid row, and no row for any benzoate salt anywhere in the paper. The preservatives Fulton did test sit together in one run — methyl paraben at 0, propylparaben at 0, phenoxyethyl paraben at 0, allantoin at 0 — and a benzoate is not among them. The only entry in the whole table whose name even contains the letters "benzo" is oxybenzone, a benzophenone sunscreen scored 0, which is an unrelated molecule and not a benzoate. So the single most-quoted comedogenicity survey in circulation does not carry this ingredient. The second full assay we can read directly, Morris and Kwan 1983 — an independent laboratory on the same 0 to 5 scale, six years before Fulton — tested 32 materials: seven lanolins, nine vegetable oils, eleven esters and five surfactants. Sodium benzoate is not one of them. Nor is it in Fulton's earlier 1984 rabbit-ear paper, whose table we hold in full, and nor is it in Nguyen, Dang and Maibach's 2007 survey, the only later rabbit-ear study we could find, which tested esters and a short list of other materials. That is all four primary inventories we hold, and the material is in none of them. Our own index of the legacy corpus files it as an ingredient we can find no assay for, which is a statement about the documents we hold, not a claim about the whole literature. That absence is not an artefact of nobody caring about the molecule. It is one of the most heavily safety-assessed preservatives in cosmetics. The US Cosmetic Ingredient Review published a final safety report on benzyl alcohol, benzoic acid and sodium benzoate in 2001 and a broader reassessment, adding benzyl benzoate, in 2017; the EU Scientific Committee on Consumer Products issued its opinion in 2005, which is the basis for the Annex V limits above; and the Joint FAO/WHO committee has set an acceptable daily intake for it as a food additive. None of those assessments measured comedogenicity. They are assessments of systemic toxicity, irritation, sensitisation and genotoxicity. An ingredient can be examined that thoroughly for one set of questions and not at all for this one, and sodium benzoate is a clean example of exactly that. Consumer comedogenicity checkers are inconsistent about it, which is itself worth reporting. One we read in full — ScanSkinAI's ingredient dictionary, fifty-plus ingredients last reviewed in June 2026 — lists phenoxyethanol but has no sodium benzoate entry at all. Absence from a comedogenicity list is not a measured zero; it means the ingredient was not flagged, which is a weaker statement. Other checkers assign a 0 to 5 number to nearly every INCI name with no disclosed method; where one of those carries a figure for sodium benzoate we traced no primary assay behind it, and we could not retrieve such a page to quote the number honestly. So read the rating precisely. Clear here means no comedogenic concern is on record — and none is. It does not mean the ingredient was tested and found inert; we traced no assay of it in either direction. The rating is an inference from an absence, and the confidence is Low because that is what an inference from an absence is worth.

What the evidence doesn’t tell you

We identified no comedogenicity assay of sodium benzoate in the assay corpus we searched or in the searches we ran for this page. That is a bounded statement about what we looked at, not a claim about the world's literature, and it is the strongest form the evidence supports. Untested is not the same as tested and cleared: if an assay were run tomorrow we would have no standing to be surprised by the result whichever way it fell. The concentration gap is real and we will not reason across it. The legacy assays did not share one protocol: Fulton's 1989 survey applied its test material at roughly 10% in propylene glycol, his 1984 paper applied liquids and soft solids as they came, and Morris and Kwan applied undiluted material to the ear canal. Sodium benzoate is capped at 0.5% in EU leave-on products, and we hold no measured in-use figure for it. Had a rabbit-ear number existed it would have been generated well above that cap — but there is no number, and no dose-response curve for a material that does not appear in the corpus, so the observation cuts no further than noting the assay and the product were never in the same place. What IS documented about this ingredient on skin is not pore-plugging. Benzoic acid and its salts are a recognised cause of non-immunologic contact urticaria: in a small number of people, direct contact produces transient wheals, redness and stinging within minutes, without an allergic mechanism. The CIR's clinical data record this for the group, noting that 2% benzoic acid elicited such a reaction while not acting as a sensitiser at that level. Nethercott and colleagues reported it specifically for sodium benzoate in 1984: three workers in a pharmaceutical plant developed transient urticaria from airborne skin contamination, their patch-test responses were no different from unexposed controls (confirming the reaction is non-immunologic), and sweating — which lowers skin pH and so raises the local concentration of benzoic acid — increased susceptibility. This is a real cutaneous effect, and it is not comedogenicity. A transient wheal is not a plugged follicle; an immediate contact reaction is not the slow keratinisation the word "comedogenic" refers to. Irritation is not comedogenicity, urticaria is not comedogenicity, and a systemic-safety conclusion is not a comedogenicity finding either. Each of these documents answers a real question about sodium benzoate; none of them answers this one. We are also not going to overclaim in the reassuring direction. The large safety file and the absence of any comedogenic flag together make it reasonable to rate the ingredient Clear, but neither is evidence that it was placed on skin, occluded, and scored for follicular keratosis and found to do nothing. We found no record of that study having been run.

Where you’ll see it

On a label it appears as Sodium Benzoate. It is a common preservative, and because it needs an acidic formula to work it turns up most in low-pH products — many cleansers, some toners and serums, and a large share of formulas marketed as paraben-free. That is a pattern that follows from its pH-dependence and the EU use limits, not a market share we have counted, and we are not going to tell you where on an ingredient list it sits, because list position below 1% is not a dose. Most public discussion of "sodium benzoate" is not about skincare at all. It is the food preservative E211, and the concerns usually attached to the name — the acceptable-daily-intake question, the debate over benzene formation in acidic drinks — are questions about ingestion and systemic exposure. Whatever their merits, they are not about pores, and a comedogenicity page has nothing to add to them.

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, read off a 400dpi render of the journal scan rather than via a list quoting it. Method: test material at 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 scored on a 0–5 scale whose own key reads 0–1 "not considered significant," 2–3 "borderline," 4–5 "considered positive." Fulton called the survey "not at all definitive but simply designed to stimulate research." CITED HERE FOR AN ABSENCE: its 220 rows contain no sodium benzoate, no benzoic acid and no benzoate-salt entry. The preservatives it does carry are the parabens (all 0) and allantoin (0); the only "benzo" entry in the table is oxybenzone (0), an unrelated sunscreen. It supports no rating of sodium benzoate in either direction.
  2. 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 0–5 scale, six years before Fulton 1989 and not a republisher of him — it contradicts him in print on several materials. Its 32 test materials are seven lanolins, nine vegetable oils, eleven esters and five surfactants. Cited purely for what it does not contain: sodium benzoate is not among them. It is one of the four primary inventories we can read directly, which is why an absence in it is worth stating.
  3. Fulton JE, 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 paper, on its own 0–5 scale, whose key reads 1–2 not significant and 3 or above considered positive, and in which liquids and soft solids were applied as they came rather than diluted to a fixed percentage. We hold its table in full and cite it here for an absence: it carries no sodium benzoate, no benzoic acid and no benzoate-salt row. The absence is verified, not assumed, and it supports no rating in either direction.
  4. Nguyen SH, Dang TP, Maibach HI. "Comedogenicity in rabbit: some cosmetic ingredients/vehicles." Cutan Ocul Toxicol 26(4):287–292 (2007) The only later rabbit-ear comedogenicity survey we could find, on a 0–4 scale, cited for what it does not contain. Its test set is esters and a handful of other materials — isopropyl palmitate and myristate, butyl stearate, decyl oleate, cetyl and stearyl alcohol, petrolatum and the rest — and no benzoate of any kind. It is the fourth of the primary inventories we hold, and the last place a number for this ingredient could have come from.
  5. Nair B. "Final Report on the Safety Assessment of Benzyl Alcohol, Benzoic Acid, and Sodium Benzoate." Int J Toxicol 20(Suppl 3):23–50 (2001) The US expert-panel SAFETY assessment, in its final published state. Concluded benzyl alcohol, benzoic acid and sodium benzoate safe for use in cosmetics at concentrations up to 5%, with data insufficient for products where the primary route of exposure is inhalation. It assesses systemic toxicity, irritation, sensitisation and genotoxicity, and it is the source of the non-immunologic contact urticaria observation quoted on this page (a few individuals; 2% benzoic acid elicited a reaction; not a sensitiser at that level). IT IS NOT A COMEDOGENICITY STUDY and we do not use it as one — safety and comedogenicity are different questions, and this document answers only the first.
  6. Johnson W, Bergfeld WF, Belsito DV, et al. "Safety Assessment of Benzyl Alcohol, Benzoic Acid and its Salts, and Benzyl Benzoate." Int J Toxicol 36(3 Suppl):5S–30S (2017) The CIR's broader reassessment, adding benzyl benzoate and the other benzoate salts to the 2001 report and reaffirming safety in the present practices of use and concentration. A later and more complete SAFETY document, cited for the current state of that assessment and for identity and function data (preservative/fragrance ingredient). Like the 2001 report it measures no comedogenicity, and assesses this ingredient as one of a chemically related group rather than in isolation.
  7. Scientific Committee on Consumer Products (SCCP). "Opinion on Benzoic Acid and Sodium Benzoate." SCCP/0891/05 (2005) The EU expert committee's SAFETY opinion, and the basis for the Annex V preservative limits in EU cosmetics (2.5% rinse-off, 1.7% oral-care, 0.5% leave-on, expressed as the acid). It notes its conclusion applies only to benzoic acid and sodium benzoate, there being no data for the other salts. A regulatory safety judgement about systemic exposure and local tolerance, not a comedogenicity measurement; cited as a safety document and only as one.
  8. Nethercott JR, Lawrence N, Roy AM, Gibson BL. "Airborne contact urticaria due to sodium benzoate in a pharmaceutical manufacturing plant." 1984. PMID 6238137 A single occupational case report, cited from its PubMed record by author, title, year and PMID — the sources we could reach disagree about which journal carried it, so we name none. Three workers exposed to airborne sodium benzoate developed transient contact urticaria; patch-test responses to sodium benzoate and benzoic acid were no different from those of unexposed controls, which the authors read as confirming a non-immunologic (rather than allergic) mechanism, and sweating appeared to raise susceptibility by lowering skin pH. Cited as the one skin effect specifically documented for this exact material — an immediate, transient urticaria, which is not comedogenicity. It is a report of three people in a factory, not a controlled study, and not a pore measurement.
  9. Cosmetics Info (Personal Care Products Council). "Sodium Benzoate" ingredient summary An industry-affiliated consumer reference maintained by the Personal Care Products Council, summarising the CIR and SCCP conclusions, the reported cosmetic functions (preservative, fragrance ingredient, corrosion inhibitor) and the JECFA acceptable-daily-intake figure. A secondary source, disclosed as industry-affiliated; used on this page for function and regulatory context, not as independent evidence of anything. It reports no comedogenicity data, and we traced none behind it.

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

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