Comedogenicity of ingredients in preparative and decorative cosmetics products is one of the most intriguing topics in the beauty community. Today we find out what comedogenicity is, whether there are ingredients that are unquestionably comedogenic, and why the product that all your friends use bothers you.
Comedones are a non-inflammatory form of acne, and they form in the pores next to the hair follicles. Apart from hair follicles, sebaceous glands are also located in these pores, and desquamation (peeling) of the skin is an important factor in the formation of comedones. With a properly regulated physiological function, exfoliated skin cells, together with the sebum secreted by the sebaceous glands, will be thrown out of the pore onto the surface of the skin.
If the function of the skin is disturbed, there is a significant risk that these "rejected" parts of the skin will remain inside the blocked pore and become a comedone, which we can consider a plug inside the pore.
It is important to distinguish two types of comedones - open and closed . Open comedones are known to everyone as blackheads, and they look like black dots in a pore on the skin. This type of blackhead is a much smaller problem compared to the closed type and can be solved by cleaning the face in beauty salons, and their occurrence can be prevented with a proper cleaning and skin care routine. Closed comedones are a paradise for the bacterium Cutibacterium acnes, which inside the closed comedone, i.e. with a lack of oxygen, will break down sebum lipids into free fatty acids that have a pro-inflammatory effect and will lead to the formation of inflammatory acne.
The comedogenicity of a particular ingredient actually refers to the potential for the application of that ingredient to clog the pores and, for this reason, to develop a comedone within it. It is important to emphasize that comedogenicity is a relative term for several reasons.
The first reason is the fact that a certain ingredient will not have the same comedogenic potential for every person, taking into account the person's skin type. In general, people with an oily skin type are much more susceptible to the formation of comedones, and if such a person's skin is more sensitive, the potential for the formation of comedones becomes significantly higher. For this reason, a certain ingredient in such a person can cause comedones and even acne very quickly, while the same ingredient in a person with insensitive and dry skin that does not secrete a lot of sebum will not cause any problems.
Another important thing when studying comedogenicity is product formulations. All ingredients are not equally comedogenic, and the composition of the product can affect to what extent the product itself will be comedogenic. Some moderately comedogenic ingredient, for example, in a formulation in which it is in a high concentration and there is another comedogen next to it, becomes much more unsafe to use. The same ingredient in a formulation in which it is the only comedogen, and in addition it is in a low concentration (it is at the bottom of the list of ingredients) will not cause problems, except for the most sensitive skin.
To determine the comedogenicity of ingredients, the gold standard was the rabbit ear test. Such tests were previously used to determine the adverse effects of topical application of certain chemicals, and were later transferred to testing cosmetic products and raw materials. Today, comedogenicity is increasingly tested on human skin ( patch test ).
We mentioned that the comedogenicity of the ingredients is relative. In addition to the previously stated reasons for such a claim, the questionable possibility of proper testing now arises. Most of what is considered comedogenic has been considered so since the early days and the first studies of comedogenicity on the rabbit's ear conducted by Fulton when he added marks from 0-5 to raw materials, where 0 means non-comedogenic and 5 extremely comedogenic. What the apps don't tell you yet, and neither does the ingredient list, is how the raw material was extracted and processed before it was incorporated into the product. If the raw material is fractionated (separated into low-molecular and high-molecular fractions), hydrogenated, refined or, for example, PEG-ilylated (polyethylene glycol addition), its comedogenic potential can be significantly reduced.
There is no list of ingredients that the product must not contain in order to be labeled as non-comedogenic. Therefore, before certain groups of raw materials or raw materials that are considered comedogenic will be listed in this text, it is necessary to state that this list of raw materials was not taken from any specific database determined by thorough scientific tests or confirmed by a specific regulatory agency. Most often, various oils obtained from natural sources are cited as comedogens, especially coconut oil, castor oil, and coconut, cocoa, and shea butter. These raw materials are extremely lipophilic and act as occlusives, which is why they are attributed with a higher comedogenic potential. Lanolin itself is considered a strong comedogen, but its acetylated and pegylated variants are milder comedogens, while jojoba oil and olive oil are considered moderate comedogens, so the negative effects will depend more on the skin type and the concentration in the product. Argan, macadamia and borage oils have not been sufficiently tested, and their comedogenic potential cannot be determined with certainty.
Certain derivatives of isopropyl alcohol and fatty acids (isopropyl-myristate, isopropyl-linolate, isopropyl-myristate) are also comedogenic, but it should be borne in mind that their concentration in the product, depending on their function, can vary greatly. And certain fatty acids such as lauric or eicosanoic acid can cause acne in more sensitive skin. It is a common misconception that polysorbate emulsifiers (Polysorbat 20, Polysorbat 80) are comedogenic, which, at least according to the most extensive research into the ingredients' comedogenicity, is not a true statement.
The comedogenicity of tocopherol (vitamin E), as well as vitamin A and vitamin D, the most common lipophilic vitamins present in cosmetic products, strongly depends on the derivative present in the product. This list could go on and take an extremely long time, but in addition to highlighting some of the most frequently mentioned ingredients, we state that the entire table was made during the previously mentioned most thorough research on comedogenicity, present in the work listed as the first reference in the literature used for this article.
Given that today information is very easily available to everyone, there are numerous concerns and misconceptions associated with the use of a large number of products. It is obvious from the article that comedogenicity is a very complex and, one could say, insufficiently adequately addressed problem.
It is important to keep in mind that each raw material and each product will not affect the skin of each individual in the same way, depending on its type and sensitivity. It is recommended that people with sensitive and oily acne-prone skin definitely check the composition of products and comedogenic ingredients, keeping in mind that there are numerous applications available today that follow the same guidelines and are by no means a concrete and 100% safe source. Until more concrete methods of determining comedogenicity are found, it remains only to choose products in an informed manner.
LITERATURE:
- Fulton IS. Comedogenicity and irritation of commonly used ingredients in skin care products . J. Soc. Cosmetics. Chem. , 1989, 40, 321-333
- Fulton JE et al. Comedogenicity of current therapeutic products, cosmetics, and ingredients in the rabbit ear. J Am Acad of Dermatol , 1984, 10, 96–105
- Draelos Z, J DiNardo J. A re-evaluation of the comedogenicity concept, J Am Acad Dermatol , 2006, 54, 507–512