Isopropyl myristate comedogenic rating: what the number means

Reviewed October 10, 2026

The short answer

In a 1989 survey of skin care ingredients by Fulton, isopropyl myristate scored 5 on a 0 to 5 comedogenicity scale and 3 on the paper's irritancy grade. That is the top of the comedogenic scale. The test used the rabbit ear, an animal model. It does not tell you what a finished moisturizer will do on your face, and it does not measure how much of the ingredient is in the product.

Where do the 5 and the 3 come from?

The paper lists many ingredients with a comedogenicity grade and an irritancy grade, both from the rabbit ear. Isopropyl myristate is listed as 5 and 3. In the same table isopropyl palmitate is 4 and 1, and myristyl myristate is 5 and 2. Each ester has its own row, so one ester's number does not carry over to another with a similar name.

Why a single number can mislead

The author of the earlier 1984 rabbit-ear paper describes the model as "not an ideal animal model but is the best we have." Rabbit ears are not human facial skin, the ingredient was tested at a stated strength, and a finished product mixes it with other ingredients. We found no human acne study behind these numbers.

What the safety review says

The Cosmetic Ingredient Review assessed alkyl esters as a group in 2013. Its table for isopropyl myristate records a rabbit-ear test in which the undiluted material produced comedogenic activity, and it records minimal irritation in human testing at the formulation levels studied. The panel concluded the listed alkyl esters, which include isopropyl myristate, are safe in the present practices of use and concentration when formulated to be non-irritating. That conclusion is about safety in use, not about whether an ingredient clogs pores for a given person.

What to do with the rating

Treat the rating as one old data point. If a moisturizer with isopropyl myristate feels fine on your skin, one rabbit-ear score does not change that. If you are breaking out, the whole formula, how often you use it and your own skin matter more. Nitavera flags isopropyl myristate as a possible pore-clogging ingredient for acne-prone profiles, and says in the result that an ingredient rating is not a test of the finished product.

What not to conclude

This page does not say isopropyl myristate is unsafe, or that a product containing it will cause breakouts. It reports what one animal-model survey found and the limits that come with it.