Where we get comedogenic ratings from

Comedogenic ratings were designed to measure the likelihood of an ingredient to cause comedones. The comedogenic rating system is numbered 0 - 5; 0 is very unlikely, while 5 is highly likely.

But not all comedogenic ratings you see online come from the same place or even the same source.

We Use Ratings From Published Studies

At SkinSort, the comedogenic ratings you see on our website come from real published studies. These are usually based on tests done on rabbit ears (originally developed in the 1970s) or small-scale human studies when available. These tests attempted to determine how likely a single ingredient is to clog pores under specific conditions.

We only include comedogenic ratings when we can trace them back to a scientific source. You might see slightly different ratings on other websites and that’s often because some might estimate ratings based on anecdotal experience or assumptions.

Use Comedogenic Ratings As a Guide, Not a Rule

We include comedogenic ratings on SkinSort to help you make more informed decisions, but we always recommend considering them alongside how your own skin reacts. Everyone’s skin is different, and no single number can predict how a product will work for you.

In fact, Dr. Albert Kligman, the dermatologist who helped create the original comedogenicity scale, once said:

“One cannot determine from a reading of the ingredients whether a given product will be acnegenic or not. What matters solely is the behaviour of the product itself.”

(In other words, the overall formulation matters more than just a few individual ingredients.)

Want to Learn More?

If you’re curious about the origins and limitations of comedogenic ratings, here are some of the sources we reference:

Kligman, A.M. & Mills, O.H. Jr. (1972) – Acne cosmetica.

Kligman, A. M. (1996) - Petrolatum is not comedogenic in rabbits or humans: A critical reappraisal of the rabbit ear assay and the concept of “acne cosmetica.

Morris, W.E. & Kwan, S.C. (1983) – Use of the rabbit ear model in evaluating the comedogenic potential of
cosmetic ingredients.

Fulton, J. E. (1989) - Comedogenicity and irritancy of commonly used ingredients in skin care products