Lecithin

Lecithin (typically soy- or egg-derived phospholipids) is primarily an emollient/emulsifier and skin-conditioning agent, usually used at low-to-moderate concentrations, and it is generally well-tolerated in sensitive-skin products. Clinical experience and patch-test data suggest low irritancy overall, but rare reactions can occur (e.g., in highly reactive eczema patients or those with specific source allergies/impurities), so it is not fully inert. Given its generally gentle profile yet nonzero risk in compromised skin, it best fits a very gentle score. Safety Notes: In mass-market leave-on lotions/serums and rinse-off cleansers, lecithin is commonly used at very low levels (~0.01–0.5%) as an emollient/co-emulsifier and to aid skin feel or solubilization. Higher-strength consumer-available products (especially anhydrous balms, rich barrier creams, and phospholipid/liposome-style moisturizers) can use lecithin as a primary structurant/emulsifier in the ~2–8% range, with practical upper limits driven by texture (waxy/tacky feel), odor/oxidation risk, and emulsion stability rather than specific regulatory caps.