Is Propylene Glycol Comedogenic?
Propylene Glycol is rated 0/5 in published comedogenicity lists — rated low on published lists.
Established Source: Fulton 1989. Primary-source value (original rabbit-ear tables). Still a raw-ingredient test — concentration and formulation change real-world behaviour. How we rate
What the rating describes
Humectant, non-comedogenic.
A comedogenicity rating is a 0–5 score assigned in published ingredient testing. A 0/5 places Propylene Glycol in the lower part of those tables. The score describes the raw ingredient as tested — not a finished formula, where concentration, the rest of the ingredient list, and how the product is used all differ.
Position on a label matters too: ingredients listed near the front are usually present in larger amounts than those near the end.
When this rating can't be trusted
The 0/5 describes the raw ingredient in a rabbit-ear assay, usually at 10% in propylene glycol. It cannot tell you how much is in your product (position on the label is the only clue), what the rest of the formula does to it, or how your skin responds. Finished products containing highly rated ingredients have tested non-comedogenic on human skin (Draelos & DiNardo, JAAD 2006).
Can the 0/5 rating for Propylene Glycol be trusted?
Established This number is the primary-source value and no published disagreement is on record — as solid as a comedogenic rating gets, which is still a screening signal, not a verdict on any product. Source: Fulton 1989.
A low number does not certify a product: a formula can still clog pores through its other ingredients or their combination. Full reasoning and bibliography.
Where the rating comes from
Ratings on this site come from published comedogenicity literature in the Fulton 1989 lineage — the 0–5 tables compiled from ingredient testing and reproduced across dermatology reference lists since. Where values disagree: a named primary source (Fulton 1989) outranks later unattributed lists, so its value is shown and the others are disclosed in the note; where only compilation lists disagree, the higher-caution value is shown. We never publish an invented number, and we never present one as more certain than its source: every rating carries a confidence tier — established (primary-source value, no disagreement on record), single-source (only the reproduced compilation lists carry it), or contested (published values disagree or depend on grade and vehicle; the note says which value is shown and why). Ingredients we cannot match appear as “not in our database” — unmatched, not cleared: no published list we hold rates them under that name, and that is not a pass.
Our flag threshold follows the American Academy of Dermatology's Invitational Symposium on Comedogenicity (J Am Acad Dermatol 1989): substances scoring 0–2 in the rabbit-ear assay are unlikely to clog pores in humans, while scores above 2 warrant more caution — which is why this site flags 3/5 and up. Read the full methodology and bibliography.
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