Diglycerin

Diglycerin is a low-molecular-weight humectant used commonly around 1–10% to improve hydration and barrier function, and it is generally well tolerated in sensitive-skin formulations. Clinical and consumer-use experience shows low rates of stinging or erythema, though occasional transient discomfort can occur on severely compromised or fissured eczema skin due to osmotic effects typical of polyols. Given its strong overall tolerability but non-zero sting potential on broken skin, it fits best as very gentle rather than inert. Safety Notes: In commercial skincare, diglycerin is used as a humectant/solvent at low levels (~0.1–1%) in emulsions and cleansers to support moisturization and sensorial profile, often alongside glycerin and glycols. Mid-range use (2–10%) is common in leave-on lotions, toners/essences, and serums where it boosts hydration with a less tacky feel than high glycerin. High-strength consumer-available formulas (typically water-based gels/essences and some sheet-mask essences) can reach ~15–25% total diglycerin for intensive humectancy; higher levels are uncommon due to tackiness, osmotic feel, and formula balance rather than regulatory limits.