A re-evaluation of the comedogenicity concept.

BACKGROUND Comedogenicity is an important consideration in the development of topical medications, cosmetics, and skin care products. The concept of "acne cosmetica" was developed to link the use of certain ingredients to comedo formation. Animal models were originally used to determine the comedogenic potential of raw materials with the assumption that finished formulations containing these ingredients would also be comedogenic. Based on this assumption, dermatologists were presented with lists of substances to avoid in patients with the ability to develop comedones. OBJECTIVE We sought to use a modification of the Mills and Kligman human assay for assessing comedogenic potential of finished cosmetic products. METHODS Six individuals with prominent follicular orifices and the ability to form comedones on the upper aspect of the back were enrolled. Each person received patches to the upper aspect of the back saturated with 0.2 to 0.5 mL of the finished cosmetic study products 3 times weekly for 4 weeks. Cyanoacrylate biopsies were performed to determine the number of follicles and microcomedones per square inch. LIMITATIONS Only a finite number of finished cosmetic products could be analyzed. CONCLUSION Finished products using comedogenic ingredients are not necessarily comedogenic.