Castor Oil (Ricinus Communis)
Castor oil, which our list names Castor Oil (Ricinus Communis), is rated 1 to 2 on our list, a range whose top puts it in the low band, and the number is traced: Fulton 1989 graded it 1 and Morris and Kwan 1983 graded it 0 to 1.
Like every rating here, it is for the raw ingredient tested alone, and a label does not print how much of it a product holds.
Our list rates 4 castor oil derivatives separately, each with its own number. See every castor oil entry.
Is castor oil comedogenic?
Castor Oil is rated 1–2 on the comedogenic scale: our list gives it a range from 1 to 2, and the band follows the 2 at the top. The rabbit-ear studies we have read give it less: Fulton 1989 gave it 1; Morris and Kwan 1983 gave it 0 to 1. Our list's 2 is above all of them.
A thick, viscous oil used to lock in moisture and often used in lip glosses and soaps.
- Comedogenic rating
- 1–2 out of 5 (a range on our list)
- Band
- Low: Little plugging in the rabbit-ear test. Fulton 1989 counts 0 to 1 as not significant and 2 as borderline.
- Where the number comes from
- Traced to Fulton 1989 and Morris and Kwan 1983. The section on who rated it prints each grade.
- Composition
- Natural Oil / Oils (High in ricinoleic acid)
- Also written as
- Ricinus Communis
What a 1–2 means in practice
One and two are the low band. In the rabbit-ear test, Fulton 1989 counted 0 to 1 as not significant and 2 as borderline. A low grade on a rabbit's ear, which reacts more readily than human skin, is weak evidence of a problem on a person.
Two things change what this number is worth. Ingredients are listed in descending order of concentration, so castor oil near the top of a label matters far more than castor oil at the bottom. And the rating describes the raw ingredient on its own. A 2006 review in the Journal of the American Academy of Dermatology found that a rating for a single ingredient does not reliably predict how a finished formula behaves on human skin. The full story of the scale is here.
Who rated it
Our list is one band above the research. Our list gives castor oil 1–2. Fulton 1989 gave it 1; Morris and Kwan 1983 gave it 0 to 1. We report the list as it stands and show the papers beside it. Where the list and the research disagree.
Our list gives castor oil 1–2. These are the figures the published rabbit-ear studies we have read give it, as printed in each paper's table.
| Paper | Grade | Tested as |
|---|---|---|
| Fulton 1989 | Grade 1 | Tested as Castor oil |
| Morris and Kwan 1983 | Grade 0 to 1 | Tested as Castor Oil |
Our list's top figure, 2, is higher than anything in these papers.
Similar names, rated separately
These share a source with castor oil or carry it in their name, and each has its own rating on our list. The 1–2 on this page does not carry over to them, so check the exact name on the label.
Fungal acne
Castor Oil matches rule 4, plant or animal oil or butter , on the fungal acne checker. A plant or animal oil, mostly triglycerides. The rule comes from lab studies of what Malassezia yeast can feed on, and it is not a verdict on any product.
Common questions
- Is castor oil comedogenic?
- Castor Oil is rated 1–2 on the comedogenic scale: our list gives it a range from 1 to 2, and the band follows the 2 at the top. The rabbit-ear studies we have read give it less: Fulton 1989 gave it 1; Morris and Kwan 1983 gave it 0 to 1. Our list's 2 is above all of them.
- Is castor oil non comedogenic?
- Not exactly. Castor Oil is rated 1–2, which is the low band rather than 0. Low and non-comedogenic are different things, and only a 0 means the second one.
- What is castor oil's comedogenic rating?
- 1–2 out of 5 on our list. It is classed as Natural Oil / Oils (High in ricinoleic acid). The rabbit-ear studies we have read give it less: Fulton 1989 gave it 1; Morris and Kwan 1983 gave it 0 to 1. Our list's 2 is above all of them.
- Does castor oil cause breakouts?
- No study we have read tested castor oil for breakouts on people. On rabbit ears it graded low: Fulton 1989 gave it 1 and Morris and Kwan 1983 gave it 0 to 1. Castor oil is a common base for the oil cleansing method, where it is massaged in and wiped off. The ratings come from tests that left a substance on the skin day after day, so they say nothing direct about an oil that is wiped away, or about a blend of several oils.
- Is castor oil less comedogenic than coconut oil?
- On the published ratings, yes. Castor oil is rated 1–2 and coconut oil 4–5, which puts coconut oil in the high band. Neither number predicts how a finished product will behave on your skin.
Sources we checked this rating against
- Kligman AM, Kwong T. “An improved rabbit ear model for assessing comedogenic substances.” British Journal of Dermatology, June 1979;100(6):699–702. (opens in a new tab) The rabbit-ear assay behind published 0 to 5 comedogenicity grades.
- Fulton JE Jr. “Comedogenicity and irritancy of commonly used ingredients in skin care products.” Journal of the Society of Cosmetic Chemists, November/December 1989;40(6):321–333. (opens in a new tab) Rabbit ear. Each ingredient at 10 percent in propylene glycol unless stated, applied five days a week for two weeks, and graded 0 to 5 from the width of the follicles, measured by micrometer and under the microscope. The paper counts 0 to 1 as not significant, 2 to 3 as borderline and 4 to 5 as positive. Some grades depended on the supplier of the raw material, and some oils were also tested refined.
- Morris WE, Kwan SC. “Use of the rabbit ear model in evaluating the comedogenic potential of cosmetic ingredients.” Journal of the Society of Cosmetic Chemists, August 1983;34(5):215–225. (opens in a new tab) Rabbit ear canal, at the Revlon Research Center. Each material applied undiluted unless stated, once a day five days a week for 14 applications, and graded 0 to 5 by microscope only. The authors set out to recheck earlier results because investigators disagreed.
- Draelos ZD, DiNardo JC. “A re-evaluation of the comedogenicity concept.” Journal of the American Academy of Dermatology, March 2006;54(3):507–512. doi:10.1016/j.jaad.2005.11.1058 (opens in a new tab) Tested finished products on the backs of six people and concluded that “Finished products using comedogenic ingredients are not necessarily comedogenic.”