Understanding comedogenicity ratings and their limitations
The comedogenicity scale rates ingredients from 0 (will not clog pores) to 5 (highly likely to clog pores). However, this scale has critical limitations that most consumers do not understand. First, comedogenicity testing was historically performed on rabbit ears (the "rabbit ear assay") — rabbit skin is significantly more reactive than human facial skin, meaning many ingredients rated 2-3 may not actually cause comedones in humans. Second, concentration matters enormously: coconut oil as a pure ingredient is rated 4/5, but at 0.5% concentration in a well-formulated product, its comedogenic effect is negligible. Third, formulation context changes individual ingredient behaviour — an ingredient that is comedogenic in an oil-based formulation may be non-comedogenic in a water-based gel. The practical approach: avoid ingredients rated 4-5 in leave-on products (especially foundations and primers that sit on skin for 8-12 hours). Ingredients rated 2-3 are generally safe in rinse-off products and in formulations where they represent less than 2% of the total composition. Key ingredients to avoid in acne-prone routines: isopropyl myristate (5/5), cocoa butter (4/5), coconut oil (4/5), wheat germ oil (5/5), acetylated lanolin (4/5), and isopropyl palmitate (4/5). These are commonly found in affordable Indian makeup products.