Ingredient ratings / Glycerin

Is glycerin comedogenic? What the pore-clogging tests found

By Skinredients · Checked against the sources 2026-10-16

Label name

Glycerin

Also listed as

glycerol, glycerine

Comedogenic grade

0 / 5 · Not significant (0) or negative

Tests

• Fulton 1989: comedogenic 0/5, irritancy 0/5 — rabbit ear, 10% in propylene glycol

What the tests found

Glycerin was graded in James Fulton’s 1989 rabbit-ear survey [1]. In the survey’s standard test, 10% in propylene glycol (method), it scored the lowest possible result on both scales: 0 for pore clogging and 0 for irritation. The propylene glycol carrier also graded 0, and Fulton notes it was non-irritating and non-comedogenic “lot after lot” [1].

Fulton gives a reason why a molecule like glycerin would not be expected to react. He proposed that an ingredient must first get into the follicle. He thought penetration was most likely for molecules that dissolve fairly well in both water and oil, with an HLB (water/oil balance) of about 10 to 12 and a molecular weight between 200 and 300. Glycerin is a small, very water-loving polyol, so it falls outside that profile. Glycerin sits with the glycols and sugars in Fulton’s table, and he writes that “the pure sugars are noncomedogenic” [1].

The catch: glycerin vs. “glyceryl” ingredients

The same paragraph of Fulton’s paper gives the warning that matters most for reading labels. Sugars and polyols “combined with penetrating fatty acids” may become follicular irritants. A combination with another irritant can raise the grade further [1]. His table shows how much the result depends on what is attached to the glycerin [1]:

Fulton links the higher result for glyceryl stearate SE to the sodium or potassium stearate added to make it self-emulsifying [1]. A second lab, Morris & Kwan, graded plain glyceryl stearate 2 when tested at 50% in mineral oil [2]. Seeing “glycer-” on a label therefore tells you little until you read the rest of the name.

Where the evidence is weaker

• One test, one concentration. No other lab in our sources graded glycerin itself on the 0-5 scale.
• Dose. Many products contain several times the 10% that was tested (see below).
• No pore-clogging data in the CIR review. The Cosmetic Ingredient Review’s 2019 safety assessment summarizes the animal and human data on glycerin, but it reports no pore-clogging tests [3].
• Rabbit vs. human. The rabbit ear is the more sensitive model [4] (why), so a 0 there is unlikely to underestimate the human result.

Where it shows up, and how much

Glycerin is one of the most widely used cosmetic ingredients. The CIR 2019 assessment (Int J Toxicol 38 Suppl 3) reports [3]:

• Number of products: 15,654 in FDA voluntary registration data from 2014, making it the third most frequently reported ingredient after water and fragrance.
• Maximum concentrations, by product type: 79.2% in leave-on products, 99.4% in rinse-off products and 47.9% in products diluted for the bath.
• Maximum concentrations, other categories: 40.6% in eye lotions, 21% in baby products and 17.9% in suntan products.

The report’s summary section gives slightly different maximums (78.5%, 68.6% and 47%). The figures above are the ones in its use table.

US OTC rules allow glycerin as a skin protectant active ingredient at 20 to 45 percent [5].

If you want to avoid it

A 0 can’t be beaten on Fulton’s scale, so switching humectants won’t lower the grade. Other humectants that matched it in the same survey include propylene glycol, sorbitol, sodium PCA, sodium hyaluronate and panthenol. Butylene glycol graded 1. The more useful check on a label is the full ingredient name: glyceryl and polyglyceryl esters carry their own, sometimes much higher, grades.

Sources

1. Fulton JE Jr. Comedogenicity and irritancy of commonly used ingredients in skin care products. J Soc Cosmet Chem. 1989;40(6):321-333. Table I, p. 324, and discussion pp. 323, 327, 329. https://library.scconline.org/v040n06/13
2. Morris WE, Kwan SC. Use of the rabbit ear model in evaluating the comedogenic potential of cosmetic ingredients. J Soc Cosmet Chem. 1983;34(5):215-225. Table IV. https://library.scconline.org/v034n05/1
3. Becker LC, et al. Safety Assessment of Glycerin as Used in Cosmetics. Int J Toxicol. 2019;38(Suppl 3):6S-22S. doi:10.1177/1091581819883820. Cosmetic Ingredient Review. https://cir-reports.cir-safety.org/view-attachment?id=ad7dbaa1-8e74-ec11-8943-0022482f06a6
4. Mills OH Jr, Kligman AM. A human model for assessing comedogenic substances. Arch Dermatol. 1982;118(11):903-905. https://pubmed.ncbi.nlm.nih.gov/7138047/
5. 21 CFR 347.10, Skin protectant active ingredients, paragraph (h) (2025 edition). https://www.govinfo.gov/content/pkg/CFR-2025-title21-vol5/xml/CFR-2025-title21-vol5-sec347-10.xml

Comedogenic grades describe single raw materials tested in a lab, usually on rabbit ears. They are a guide for acne-prone skin, not a prediction for any product or person, and this page is not medical advice. How the scale works.