Ingredients that cause acne? Or should you use comedogenicity ratings?
If you are interested in skincare, and especially if your skin is acne-prone, you probably have heard that some ingredients are considered comedogenic. People believe that skincare products containing these comedogenic ingredients “break them out” or, in other words, cause acne spots and comedones (blackheads and whiteheads). Many consumers go to great lengths to check the ingredient lists of the products they use against comedogenicity ratings to make sure that their skincare does not contain the “offenders”.
In reality, ingredient comedogenicity ratings tell us little about the actual potential of a product to cause or aggravate acne. Here is why.
First of all, when people say that a product “breaks them out” they usually mean that they notice pimples a day or two after using it. This is simply not enough time for comedones to form (it takes over two weeks). If a product “breaks you out”, it is most likely due to the irritant reaction in your skin rather than the product “clogging pores”. An ingredient and a product can be irritating (and therefore lead to breakouts) but not comedogenic. And the opposite is true: a product or an ingredient can be comedogenic without being a high-risk irritant.
When it comes to comedogenicity, the truth is that most ingredients are not comedogenic in the concentrations typically used in cosmetic products, apart from “single ingredient” products like oils and butters made primarily from a few ingredients, e.g. cocoa or shea butter, or some pure face oils. The tendency of ingredients to cause comedones is dose-dependant: the higher the concentration of an ingredient, the higher the chance that it will lead to clogged pores. For the absolute majority of cosmetic ingredients, they are shown to be non-comedogenic in concentrations below 10-20% (which is the case for most ingredients in most formulations).
Things are not so simple though: while single ingredients are rarely comedogenic in the concentrations used, the whole skincare product can be comedogenic - even if it does not contain a single ingredient that is known to cause comedones on its own. For example, research shows that makeup (for example, some bronzing powders and foundations) and sunscreens are the most risky product categories when it comes to comedogenicity. The trouble is that it is nearly impossible to predict if a product will be comedogenic based on the ingredient list. The outcome (comedogenic or not) depends not only on the product, but also the individual’s skin - their natural pore size, as well as the chemical composition of their sebum, which can also change depending on many factors including menstrual cycle, age, stress levels or sun exposure.
If checking the ingredient list for comedogenic ingredients on all your products is not useful, what can one do to minimize the risk of getting comedones or breakouts from cosmetics? The first step is to minimize the risk that the product will irritate your skin - this is why it is a good idea to treat your skin as sensitive, even if you are lucky enough not to experience any prominent adverse reactions to cosmetics (a breakout would qualify as one though). The calmer your skin and the stronger your barrier function, the lower the chances that you will experience a breakout.
If your skin is acne-prone, it is also a good idea to avoid “single ingredient” products including concentrated face oils and butters and use traditional moisturizing lotions instead.
If you notice a sudden increase in breakouts or comedones, first check if any of your skincare might be causing an irritation. This includes the product ingredients, as well as how frequently you are using it (for example, over-washing and over-exfoliating are one of the most frequent causes of skin irritation).
Then, try switching up your sunscreen and makeup products as these product categories have a higher risk of being comedogenic (just please make sure not to go sunscreen free if you are exposed to direct or indirect sun).
If these two steps do not help, you might try your luck with checking the comedogenicity rating of the ingredients in your products to create your personal “suspect circle” (you can add these ingredients to your “Avoid list” on whatsinmyjar.com to make the tracking easy). While it is unlikely that a single ingredient has led to your comedone formation, you might be able to identify a pattern such as, for example, “sunscreens with isopropyl myristate tend to clog my pores”. Identifying patterns like this can work because formulations within a single product category (e.g. sunscreens, or makeup foundations) are often similar, and this approach might help you avoid the types of products that do not agree with your skin.
How about products that explicitly promise to be "non-comedogenic" or say that they "will not clog pores"? While skincare brands are required to substantiate these claims in some shape or form, no reliable standard exists in the industry and these claims are meaningless. It is simply another marketing technique, and it is best not to rely on it when choosing your skincare.
A re-evaluation of the comedogenicity concept https://www.sciencedirect.com/science/article/abs/pii/S0190962205046001
Comedogenicity in Rabbit: Some Cosmetic Ingredients/Vehicles https://www.tandfonline.com/doi/abs/10.1080/15569520701555383
Comedogenicity of current therapeutic products, cosmetics, and ingredients in the rabbit ear https://pubmed.ncbi.nlm.nih.gov/6229554/
Acnegenicity and Comedogenicity Testing for Cosmetics https://www.academia.edu/download/49059388/Barel__Paye__Maibach_-_Handbook_of_Cosmetic_Science_and_Technology_0824741390.pdf#page=854
Myths, Truths, and Clinical Relevance of Comedogenicity Product Labeling https://jamanetwork.com/journals/jamadermatology/article-abstract/2687007
Photo by Timothy Dykes