Comedogenic Scale

 

The comedogenic scale was developed in the late 1970s by dermatologist Dr. Albert Kligman (along with researchers like Dr. James Fulton), who used the "rabbit ear model" to test for pore-clogging ingredients.

The scale, typically ranging from 0–5, was designed to evaluate the acne-causing potential of ingredients.

Methodology: Dr. Kligman utilized the rabbit ear assay (REA), testing substances on the inner ear of rabbits to observe microcomedone (clogged pore) formation.

The scale ranks ingredients from 0 (non-comedogenic/unlikely to clog) to 5 (highly comedogenic/likely to clog).

While groundbreaking, the original 1970s studies are often considered limited today because rabbit ear skin is significantly more sensitive than human facial skin, leading to potential inaccuracies in current cosmetic applications.

Another approach would be evaluating oils fatty acid profiles. 

Fatty Acid Profiles: For oils, looking at the linoleic vs. oleic acid ratio can also be helpful. 

Research shows that individuals with acne prone skin often have a deficiency in linoleic acid within their sebum. 

This deficiency causes the skin's natural oils to become thicker and stickier, thus increasing the likelihood of clogged pores and the formation of comedones.

Oils high in linoleic acid are generally better tolerated and can help balance the sebum from acne-prone skin; making it lighter and less likely to cause breakouts.

1: Very low likelihood of clogging.

2: Moderately low risk; safe for most.

3: Moderate risk; can be problematic for acne-prone skin.

4: Fairly high risk; likely to cause breakouts for many.

5: Highest risk; almost guaranteed to clog pores.

Argan oil - 0: 

Linoleic - 31-36%

Oleic - 43 - 49%

Fractionated coconut oil - 2-3

Raw coconut oil - 4

Linoleic - 1-3%

Oleic - 5 - 10%

Sunflower seed oil - 0

Linoleic - 60 - 75 %

Oleic - 14 - 20 %

Grape seed oil - 1

Linoleic - 60 - 75 %

Oleic - 15 - 20 %

Rose hip oil 1-2

Linoleic - 44 - 55 %

Oleic - 13 - 16 %

Pomegranate seed oil - 1

Linoleic - 5-10 %

Oleic - 5-10 %

Kiwi seed oil - 1

Linoleic - 15%

Oleic - 12 %

Cranberry seed oil - 2

Linoleic - 30 - 35 %

Oleic - 20-25%

Cucumber seed oil -1

Linoleic - 60 - 70 %

Oleic - 15-20%

Watermelon seed oil - 0

Linoleic - 60-65%

Oleic - 15 - 20 %

Red raspberry seed oil -1

Linoleic - 50 - 55 %

Oleic - 10 - 15 %

Castor oil -1

Linoleic - 3-5 %

Oleic 3-6 %

Strawberry seed oil -0

Linoleic - 40-50%

Oleic - 15-20%

Apricot kernel oil - 2

Linoleic - 25 - 30 %

Oleic - 60 - 70 %

Blueberry seed oil - 1

Linoleic - 40 - 45 %

Oleic - 20 - 25 %

Jojoba - 2

Linoleic - 5%

Oleic - 10%

Maracuja oil - 1-2

Linoleic - 65 - 80%

Oleic - 20-15 %

Olive oil - 2

Linoleic - 5-15%

Oleic - 60-80%

Pumpkin seed oil - 2

Linoleic - 45-60%

Oleic - 20-35%

Almond oil - 2

Linoleic - 20-30%

Oleic - 60-80%

Avocado oil - 2-3

Linoleic - 10-15%

Oleic - 60-80%

Evening primrose oil - 2

Linoleic - 70-75%

Oleic - 5-10%

Hemp seed oil - 0

Linoleic - 50-60%

Oleic - 10-15%

Safflower oil - 0

Linoleic - 70-80%

Oleic - 10-15%

Carrot seed oil - 3 - 4

Linoleic - 10-15%

Oleic - 60-70%

Baobab Oil - 2 

Linoleic - 25-35%

Oleic - 30-40%

Sea Buckthorn Berry Oil - 1 

Linoleic - 5-10%

Oleic - 10-30%

Bakuchiol Oil 0-1 

Shea butter - 0 -2

Linoleic 3-8%

Oleic - 40-50%

Mango butter - 2-3

Linoleic - 2-5%

Oleic - 35-50%

Cocoa butter - 4

Linoleic - 2-4%

Oleic - 30-35%

Kokum butter - 0 - 1

Linoleic - 2%

Oleic - 30-40%

Beef Tallow - 2

Linoleic - 2-4%

Oleic - 35-45%