Myristic acid comedogenic rating: what the number means

Reviewed October 16, 2026

The short answer

In a 1989 survey of skin care ingredients by Fulton, myristic acid scored 3 on a 0 to 5 comedogenicity scale and 0 on the paper's irritancy grade. The test used the rabbit ear, an animal model. It does not tell you that a cream with myristic acid in it will cause breakouts on your skin, or that it won't.

Where does the 3 come from?

The paper lists many ingredients with a comedogenicity grade and an irritancy grade, both from the rabbit ear. Myristic acid sits among the fatty acids, with a 3 for comedogenicity and a 0 for irritancy. The same table grades its neighbors differently - lauric acid scores 4, palmitic acid 2, stearic acid 2 to 3 - so the rating belongs to this one ingredient, not to the whole group.

Why a single number can mislead

The authors of the earlier 1984 rabbit-ear paper describe the model as "not an ideal animal model but is the best we have." The 1989 paper also reports that the vehicle matters: fatty acids behaved differently in a fast-evaporating solvent than in sunflower oil, and the survey used propylene glycol as its routine diluent. A raw ingredient tested that way is not the same thing as a finished moisturizer, where myristic acid is one ingredient among many, at a concentration the label does not show.

How is myristic acid used in cosmetics?

The Cosmetic Ingredient Review assessed 102 fatty acids and fatty acid salts together in 2019. Myristic acid is discussed in that report. The panel concluded the group is safe in the present practices of use and concentration when formulated to be non-irritating and non-sensitizing. It also noted that fatty acids may cause dermal irritation. That is a safety conclusion about cosmetic use, not a statement about acne.

What to do with the rating

Treat a rating like this as one old data point. If a moisturizer with myristic acid 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 skin matter more than one ingredient. Test a new product on a small area of skin, twice daily for 7 to 10 days, before full use, and ask a clinician about ongoing acne.

What not to conclude

This page does not rate myristic acid as safe or unsafe for acne-prone skin, and it does not say a score of 3 means avoid. It reports what one animal-model survey found and the limits that come with it.