Dipropylene Glycol

Dipropylene glycol is a solvent/humectant typically used at low-to-moderate concentrations in cosmetics and is generally well-tolerated, with human patch testing showing a low rate of irritation compared with more reactive solvents. However, it can still cause stinging or irritant dermatitis in highly compromised skin barriers (e.g., active eczema) or when combined with other irritating actives, so it is not truly inert. For patient safety in severe sensitivity populations, I rate it as very gentle but not irritation-free. Safety Notes: Dipropylene glycol is used as a humectant/solvent and fragrance carrier, and in many creams/lotions/serums it appears at low supporting levels around ~0.1–2% (especially when acting mainly as a co-solvent for actives or fragrance). In consumer products it commonly sits in the mid single digits to teens as part of the solvent/humectant system, and the highest OTC levels (~20–40%) are observed in alcohol-free body sprays, mists, and some water-based perfume/fragrance or deodorant-type products where DPG is a primary carrier. It is permitted in cosmetics without a specific EU/FDA maximum concentration, so practical limits are driven by skin feel, tack, compatibility, and irritation potential rather than regulation; rinse-off products typically use lower levels than leave-on carriers.