How Do Comedogenic Ratings REALLY Work?

The comedogenic index scale has been shared and re-shared all over the internet by beauty bloggers and even other estheticians. Many people use it as a hard guide when choosing if a product is right for them. If you have been a reader or follower of mine for a while you may have noticed I have never shared this chart or information. Why? This topic is a complicated conversation and with the testing methods and no real regulation, there are a lot of holes and no guarantees!

As many of you know I am a licensed esthetician and I now work in product development for a skin care company. Learning from chemists, being aware of claims testings, understanding how ingredients work alone and within a formula are all part of my job. Saying that my thought process on this topic is a bit deeper so I will share with what I've learned. Trust me I wish it was as simple as looking at a chart to find out if something will cause blackheads or acne! 

Defining comedogenic

Comedogenic - Tending to cause blackheads or whiteheads by blocking the pores of the skin.

Non-comedogenic - Denoting a skin-care product or cosmetic that is specially formulated so as not to cause blocked pores.

Non-acnegenic - A product specifically formulated to not cause or increase acne. (This is a newer term you may start to see.)

The Comedogenic Index Scale

This index includes plant oils, waxes, butters, alcohols, esters, sugars, vitamins, herbs, antioxidants, thickeners, emulsifiers, detergents, and botanicals. Factors that go into consideration for determining the comedogenic rating are the ratio of essential fatty acids in the oil, where it's derived from and how it's expelled. Different oils contain different acids such as lauric, linoleic, linolenic, myristic, capric, caprylic and oleic. I will also note since many of these substances are plant-derived the composition will vary because of climate, soil, conditions where the plant is grown etc.

These substances are ranked on a scale from 0-5 and looks a little something like this:

0 – Not Likely to Clog Pores
1 – Low
2 – Moderately Low
3 – Moderate
4 – Fairly High
5 – High

How are comedogenic tests performed?

Keep in mind there is not a standardized or regulated testing method by any governing organization. Because of this, the results can vary significantly from ingredient to ingredient and even brand to brand with third-party testing.

Rabbit Ear Test

Ingredients are swabbed into the inside part of a rabbits ear for two weeks and the production of blackheads were assessed. This test was first performed in the 1970's and has long been the standard. However, the questionable aspect of this testing method is the skin in the ear of a rabbit is not like human skin, is far more sensitive and responded much quicker creating false positives. Also, not to forget this method isn't cruelty-free.

Human Skin Tests

1. This test is performed on the backs of human volunteers. Ingredients are applied then covered with a bandage making them penetrate a lot faster and deeper. After 4-8 weeks a surface biopsy is conducted.

There are two major pitfalls with this method. In real life usage, people aren't applying bandages or occlusive barriers over their skin after applying skin care products. Plus, the skin on the back is different than the skin on the face. Back skin is thicker and facial skin contains more hair follicles along with being more reactive.

2. If human facial testing is performed it's typically done on people with oily and/or acne prone skin with larger pores. What about people with normal, dry, sensitive or combination skin? What about smaller and medium-sized pores?

The percentage in the formula

Another factor to consider is the percentage of ingredients within a formula. For example, one of the most talked about oils is coconut oil and it at 100% concentration it ranks as a 4 on this index scale. However, when it's in a moisturizer at 1-2% concentration with a bunch of other ingredients it greatly changes the outcome and doesn't automatically mean the entire finished formula also ranks as a 4. It's called dilution!

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Your unique skin 

Let's remember we all have our own unique skin chemistry. Plus, the environment you are exposed to, pregnancy, illness or medications all play a role in how your skin will react to certain ingredients. There is no one size fits all for treating the skin. So while one person breaks out from a certain ingredient another may have great success with it.

Is the comedogenic index scale completely useless?

This is the complicated part of this conversation. It's not entirely useless and while it's not an exact science or there are ways to use it with some know how. Say you are getting clogged pores or acne all of a sudden and you're not exactly sure what's causing it. I would start by using this checklist:

  1. Look through your product ingredient lists for where comedogenic ingredients fall. Usually, the top 7 ingredients are the most concentrated. (Higher the ingredient on the list the more concentrated and the lower the less concentrated.)
  2. If you are particularly sensitive, reactive or acne/blackhead prone you may want to avoid all of these types of ingredients in any formulation. (Keeping a skin journal and doing the elimination method is great for this!)
  3. Avoid comedogenic ingredients at full concentration.
  4. Patch test behind your ear/on your neck before you slather your entire face to know for sure.
  5. Remember, body skin is different than facial skin. So you may be able to use rich butters and oils on your body and not your face.
comedogenic ratings

Last Thoughts

My reasoning for writing this blog post was is to express that just because a product has a comedogenic ingredient (based on the list) doesn't automatically make it a bad product. You could totally be disregarding the best moisturizer of your life because of this list! The comedogenic index scale should be used as a guideline and not a hard rule. Also, I am a big fan of using your own sense and knowing your own skin to make decisions about what is best for you!