Is Castor Oil Comedogenic?
Castor Oil is rated 1/5 in published comedogenicity lists — rated low on published lists.
Single-source Source: compilation. Only the reproduced compilation lists carry this number; not verified against the original table. How we rate
Also appears on labels as
- ricinus communis seed oil
- ricinus communis (castor) seed oil
What it is
Castor oil is about 90% ricinoleic acid — a hydroxy fatty acid almost unique to the castor bean. The hydroxyl group makes the oil unusually thick, glossy, and polar, which is why it dominates lipsticks and glosses despite feeling heavier than most oils.
Why it's rated 1/5
Despite the heavy feel, published lists rate castor oil 1. Texture and comedogenicity are separate properties — thickness on the fingertip says little about behavior in a follicle, and ricinoleic acid esters did not raise comedones in the classic assays the way lauric or isopropyl esters did.
Note that hydrogenated castor oil is a chemically different material — the original Fulton 1989 table grades it 1, same as plain castor oil. PEG-40 hydrogenated castor oil is different again, with no consistent published rating, so this site doesn't list one — see our rule on never inventing numbers.
On the label
Appears as Ricinus Communis (Castor) Seed Oil. Most facial exposure comes from lip products and brow/lash serums, where quantities are small and contact is localized.
When this rating can't be trusted
The 1/5 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 1/5 rating for Castor Oil be trusted?
Single-source This number comes only from reproduced compilation lists and has not been verified against the original table. Treat it as a screening signal from a copied list, not a measurement you can cite. Source: compilation.
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.
Related ingredients
- 1/5Aloe ButterAloe extract in a coconut-derived base, cited 0–1; higher kept.
- 1/5Babassu OilGraded 1 in the original Fulton 1989 table (some later unattributed lists cite 2).
- 1/5Beta CaroteneColorant/antioxidant, rated low.
- 1/5Black Currant Seed OilLinoleic-rich, cited 0–1; higher kept.
- 1/5Blueberry Seed OilCited 0–1; higher kept.
Check your whole product
Paste the full ingredient list to see every flagged ingredient at once.