Isopropyl Myristate
Isopropyl myristate is rated 5 on our list, in the high band, and the number is traced: Fulton 1989 graded it 5 and Morris and Kwan 1983 graded it 3 to 4.
On strength, Kligman 1996 reports that below 15 percent it was not comedogenic in rabbit or human tests, from observations he did not publish, and gives no grade.
Is isopropyl myristate comedogenic?
Isopropyl Myristate is rated 5 on the comedogenic scale, which is the high band.
A synthetic oil used to cut the greasy feel of lotions. Fulton 1989 used it as the reference substance for a grade of 5 in the rabbit-ear test.
- Comedogenic rating
- 5 out of 5
- Band
- High: Clear plugging in the rabbit-ear test. The first band to check in a leave-on product.
- Where the number comes from
- Traced to Fulton 1989 and Morris and Kwan 1983. The section on who rated it prints each grade.
- Composition
- Ester / Emollient / Fatty Acids & Derivatives
- Also written as
- No common variants recorded
What a 5 means in practice
A 4 or 5 is the top of the scale. In the rabbit-ear test, Fulton 1989 counted 4 to 5 as a clear positive: the ingredient plugged the follicles, and did so repeatably. A person's skin reacts less readily than a rabbit's ear, and a product holds far less of the ingredient than the test did, so treat this band as the first thing to check in anything that stays on your skin. It does not prove the ingredient will cause a breakout. A rinse-off product is on the skin for seconds.
Two things change what this number is worth. Ingredients are listed in descending order of concentration, so isopropyl myristate near the top of a label matters far more than isopropyl myristate 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 gives isopropyl myristate 5. 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 5 | Tested as Isopropyl myristate |
| Morris and Kwan 1983 | Grade 3 to 4 | Tested as Isopropyl Myristate (50% in propylene glycol) |
Kligman 1996 calls undiluted isopropyl myristate "definitely comedogenic", but reports that below 15 percent it was not comedogenic in rabbit or human tests, from unpublished observations; no grade given.
Ahn and colleagues 1985 reports severe comedogenicity in the rabbit ear canal, in an abstract that gives no 0 to 5 grade.
Our list's figure is within what these papers report.
Others in the same family
Where isopropyl myristate comes up on this site
Fungal acne
Isopropyl Myristate matches rule 2, ester of a C12 to C24 fatty acid , on the fungal acne checker. An ester of myristic acid, C14. 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 isopropyl myristate comedogenic?
- Isopropyl Myristate is rated 5 on the comedogenic scale, which is the high band.
- Is isopropyl myristate non comedogenic?
- No. Isopropyl Myristate is rated 5 on the comedogenic scale, which is the high band. That is a published rating for the ingredient rather than a verdict on any product containing it.
- What is isopropyl myristate's comedogenic rating?
- 5 out of 5 on our list. It is classed as Ester / Emollient / Fatty Acids & Derivatives.
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.
- Kligman AM. “Petrolatum is not comedogenic in rabbits or humans: a critical reappraisal of the rabbit ear assay and the concept of acne cosmetica.” Journal of the Society of Cosmetic Chemists, January/February 1996;47(1):41–48. (opens in a new tab) Petrolatum on the faces of twenty acne patients for eight weeks, plus remarks on the revised rabbit-ear assay. No 0 to 5 grades; several statements rest on what the paper calls unpublished observations.
- Ahn HY, Myung KB, Hahm JH, Kook HI. “An experimental study on comedogenicity of several external contactants.” Korean Journal of Dermatology, October 1985;23(5):620–629. (opens in a new tab) Rabbit ear canal; in the abstract’s words, the materials were applied to one ear canal of rabbits "for 6 weekdays for 2 weeks". Read at abstract level: the full text is not online. The abstract sorts ingredients into none, mild, moderate and severe with no 0 to 5 grade, and lists propylene glycol under both none and moderate. Kligman 1996 says that putting test materials inside the ear canal gave false positives in his own 1972 study, because loose horny material collects in the follicles there.
- 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.”