Is glycerin comedogenic? Graded 0, and a humectant, not an oil
Glycerin was graded 0 for comedogenicity and 0 for irritancy in James Fulton’s 1989 rabbit-ear table, and it is not on the published comedogenic list this site uses. It is a humectant — a water-binding alcohol with three hydroxyl groups — rather than an oil, and US rules allow it as a skin-protectant active at 20 to 45 per cent.
This page covers what glycerin is, where its grade comes from and what the scale means, how US regulations list it, why the fungal-acne rule holds it out by name, and what a grade of 0 does not tell you about a finished product.
What glycerin is, and why it is not an oil
Glycerin is a simple alcohol with three hydroxyl groups, which is why it binds water rather than forming an oily film. A 2014 review of moisturisers classes it as a humectant, alongside sodium lactate, hyaluronic acid, sorbitol and urea, and calls it the most effective humectant for hydrating the outer layer of skin.
That classification is the whole reason glycerin answers the pore question differently from the lipids it is usually blended with. Comedogenic grades cluster among oils, butters, esters and waxes; glycerin is none of those, and a 2008 review describes it as a trihydroxy alcohol used in topical dermatological preparations for many years.
| Name on the label | What it is | How this site’s checkers read it |
|---|---|---|
| Glycerin | The INCI name used in ingredient lists | Recognised, not on the comedogenic list; a named Malassezia exception |
| Glycerine | An alternative spelling of the same substance | The same entry as Glycerin in every checker |
| Glycerol | The chemical name, common in research papers | The same substance; rarely printed on a cosmetic label |
| Glyceryl Stearate SE | An emulsifier built from glycerin and stearic acid — a different ingredient | On the comedogenic list with a rating of 3 |
The last row is the one that causes confusion. A label that reads Glyceryl Stearate SE is not
listing glycerin twice: it names an ester that the comedogenic list rates 3, and the shared prefix
says nothing about how the two behave.
Where glycerin sits on comedogenic tables
Glycerin carries a 0 for comedogenicity and a 0 for irritancy in Fulton’s 1989 table, the lowest grade on both scales. Each material in that study was tested at a 9-to-1 dilution in propylene glycol, and on the paper’s own scale anything from 0 to 1 is not considered significant.
0
| Material in Fulton’s 1989 table | Comedogenicity | Irritancy |
|---|---|---|
| Glycerin | 0 | 0 |
| Glyceryl stearate SE | 3 | 2 |
No FDA, EU or other regulator certifies comedogenic lists, and the rabbit-ear assay is more sensitive than human skin. How comedogenic ratings are produced sets out the method and the concentration effect, which matters less for glycerin than for most materials, because a 0 has nowhere lower to go.
How US regulations list glycerin
Glycerin appears in US regulations in two roles, and neither is about pores. The skin protectant rule lists it as an over-the-counter drug ingredient at 20 to 45 per cent, and the food rules list it as generally recognized as safe when used in accordance with good manufacturing practice.
| Document | What it says about glycerin |
|---|---|
| 21 CFR 347.10(h) | An allowed skin-protectant active ingredient at 20 to 45 percent |
| 21 CFR 182.1320 | Generally recognized as safe in food under good manufacturing practice |
| 21 CFR 701.3 | Not glycerin-specific: cosmetic ingredients are listed in descending order of predominance |
The two US listings describe glycerin as a skin protectant and as a food substance. Neither is a statement about pores, and a comedogenic grade is not a regulatory category at all.
The Cosmetic Ingredient Review expert panel concluded in 2019 that glycerin is safe as a cosmetic ingredient in the practices of use and concentration it described. That is the panel’s conclusion, quoted with its limits, and it does not address comedogenicity.
Why the fungal acne rule holds glycerin out
Glycerin is on the named exception list of the Malassezia rule this site publishes, together with butylene glycol and propylene glycol. The yeast uses fatty acids of roughly C11 to C24; humectants carry no fatty-acid chain, so the exception list states the answer outright.
Comedogenic list
Glycerin is recognised and not on the list. Its traceable grade is 0, and the list holds only entries rated 1 or higher as flags.
Malassezia rule
A named exception: a humectant, not a lipid. Glyceryl esters such as glyceryl stearate are a different case and the ester pattern can match them.
What neither screen knows
The oils and esters glycerin is blended with, their proportions, and how thickly the product is applied.
The fungal acne checker prints its exceptions in full, and the squalane guide covers the lipid that rule also holds out by name.
What a grade of 0 cannot tell you
A grade of 0 describes glycerin tested on its own, and a cream is never glycerin on its own. Human testing of finished products found that products made with comedogenic ingredients are not necessarily comedogenic themselves, and the reverse caution applies when glycerin sits beside esters rated 3 or 4.
| Question | What the grade answers | What it leaves open |
|---|---|---|
| Is glycerin comedogenic as tested? | Graded 0 at 10% in a rabbit-ear assay | Whether every skin responds the same way |
| Is this glycerin product pore-clogging? | Nothing directly | The other ingredients and their proportions |
| Is glycerin suitable for fungal acne? | Nothing — a different question | Answered here only as a rule exception |
The pore-clogging ingredients checker reads every line of a label against the full list, which is the practical answer to the question a single grade cannot settle.
What this page will not tell you
This page reports a published grade, two regulations and what the checkers on this site do with glycerin. It does not say whether a glycerin product will suit your skin, and it gives no verdict on any named product. Persistent breakouts are worth taking to a dermatologist.
Common questions
Does glycerin clog pores
Is glycerin fungal acne safe
Is glycerine the same as glycerin
Why is glycerin near the top of so many ingredient lists
When is a comedogenic grade the wrong thing to check for glycerin
Sources
Every factual claim on this page that can be checked against a document is listed here with the document it comes from.
- Comedogenicity and irritancy of commonly used ingredients in skin care products — Table IJournal of the Society of Cosmetic Chemists, 1989 (Fulton JE Jr.), SCC Media Library · library.scconline.orgThat glycerin was graded 0 for comedogenicity and 0 for irritancy in the rabbit-ear table.
- Comedogenicity and irritancy of commonly used ingredients in skin care products — methodsJournal of the Society of Cosmetic Chemists, 1989 (Fulton JE Jr.), SCC Media Library · library.scconline.orgThe paper's reading of its scale — 0 to 1 not significant, 2 to 3 borderline, 4 to 5 positive — and the 9-to-1 dilution in propylene glycol used for testing.
- 21 CFR 347.10 — Skin protectant active ingredientsElectronic Code of Federal Regulations (eCFR) · ecfr.govThat glycerin at 20 to 45 percent is an allowed active ingredient in US over-the-counter skin protectant products, paragraph (h).
- 21 CFR 182.1320 — GlycerinElectronic Code of Federal Regulations (eCFR) · ecfr.govThat glycerin is listed as generally recognized as safe in food when used in accordance with good manufacturing practice.
- 21 CFR 701.3 — Designation of ingredientsElectronic Code of Federal Regulations (eCFR) · ecfr.govThat US cosmetic labels must declare ingredients in descending order of predominance.
- Moisturizers for acne: what are their constituents?Journal of Clinical and Aesthetic Dermatology, 2014 (PMC) · pmc.ncbi.nlm.nih.govThat glycerin is classed as a humectant alongside sodium lactate, hyaluronic acid, sorbitol and urea, and that the review calls it the most effective humectant for stratum corneum hydration.
- Glycerol and the skin: holistic approach to its origin and functionsBritish Journal of Dermatology, 2008 (PubMed) · pubmed.ncbi.nlm.nih.govThat glycerol is a trihydroxy alcohol long used in topical dermatological preparations, with reported effects on stratum corneum hydration, barrier function and mechanical properties.
- Safety Assessment of Glycerin as Used in CosmeticsInternational Journal of Toxicology, 2019 — Cosmetic Ingredient Review (PubMed) · pubmed.ncbi.nlm.nih.govThat the Cosmetic Ingredient Review panel concluded glycerin is safe as a cosmetic ingredient in the practices of use and concentration it described — quoted as the panel's conclusion, not as this site's.
- A re-evaluation of the comedogenicity conceptJournal of the American Academy of Dermatology, 2006 (PubMed) · pubmed.ncbi.nlm.nih.govThe finding, from human testing of finished products, that products made with comedogenic ingredients are not necessarily comedogenic themselves.