The use of oils in skin care is widely misunderstood. Many people equate all oils to the sebum produced naturally by the skin, which is often scapegoated as a direct cause of acne. However, oils are a vast category of substances with an array of properties – many of which can benefit the skin care routines of individuals of all skin types. Determining the usefulness of a specific oil in your routine starts with evaluating its likelihood to sit in the skin’s pores.

Acne cosmetica is a class of acne attributed to the use of cosmetic products which block follicular ducts, causing clogging of sebum and dead skin cells. This clogging of natural materials is what leads to the formation of comedones.  Common culprits of this type of acne are ingredients which we deem “comedogenic,” or acnegenic. Comedogenicity is scaled from values of zero through five, along which ingredients are rated based on their likelihood toclog up pores and enable build-up. Ratings of zero, one, and two are considered non-comedogenic and ratings of three, four, and five are typically deemed comedogenic. However, these ratings are not definite standards of a substance’s ability to cause acne. 

It is important to note that these ratings are not absolute determinants of how a substance will affect your skin. For starters, comedogenicity studies originated in the 1970’s with the Rabbit’s Ear Test. Pure ingredients were applied to the inner ear skin of a rabbit, and the patch was later evaluated for a number of clogged pores. This data, although still applied today, is questionable because rabbit’s skin is generally more prone to clogging than human skin. Modern studies in this field typically use skin of the human arm or back. These areas, like the rabbit’s ear, have pores and sebum production levels which vary from those of the face, making outcomes uncertain in their applicability to facial skin care. Additionally, dilution is a huge factor in determining the overall comedogenicity of a product – rarely do we apply any ingredient in 100% pure concentration. These factors led to misconceptions regarding an array of substances which have since had their comedogenicity reevaluated and rescored, although current standards and research practices are still questionable. 

Despite the lack of regulation in rating comedogenicity, scores are widely accepted as they, at the very least, explain a spectrum along which ingredients may block up pores. In regard to oils, those with high comedogenic scores tend to be those with longer fatty acid chains. These larger molecules are more likely toclog follicular ducts and enable a build-up of sebum and dead skin cells, eventually leading to a break out. Therefore, those with oilier skin should stick to topical oils on the lower end of the comedogenicity scale, as they are less likely to block pores and trap sebum in the skin. Drier skin types, who experience a deficit of natural oil production, may benefit from using oils higher in comedogenicity rating as they can help maintain moisture levels. It depends on your skin’s individual needs, and what you find works best for you.

Comedogenicity is a useful concept in considering the likelihood of a substance to influence breakouts. However, the methods by which comedogenicity is determined are faulty and the resulting ratings should not be taken as absolute. The overall formulation of a product greatly influences the way an ingredient interacts with your skin. Products containing oils can have a wide array of benefits, and they can’t be a direct cause ofAcne cosmetica. There’s no need to be scared of incorporating topical oils into your daily routine – use comedogenicity ratings as a guide and explore what works best for you!

Sources: 

1. Draelos, Zoe Diana, and Joseph C. DiNardo. "A re-evaluation of the comedogenicity concept." Journal of the American Academy of Dermatology 54.3 (2006): 507-512.
2. Kligman, Albert M., and Otto H. Mills. "Acne cosmetica." Archives of Dermatology 106.6 (1972): 843-850.
3. Maarouf M, Saberian C, Shi VY. Myths, Truths, and Clinical Relevance of Comedogenicity Product Labeling. JAMA Dermatol. 2018;154(10):1131–1132.