Triethanolamine

Triethanolamine is primarily a pH adjuster/emulsifier used at low concentrations (often ~0.5–3%) to neutralize fatty acids and stabilize formulas; at these levels it is generally well tolerated. However, clinical experience and patch testing data show it can cause irritant contact dermatitis—especially in compromised barriers (eczema, post-procedure) or when used to raise product pH—and it has occasional sensitization reports. Given the non-trivial irritation potential in reactive patients and its routine presence in leave-on products, a mild risk score is warranted for patient safety. Safety Notes: In commercial skincare, triethanolamine (TEA) is most often used at low levels (~0.05–0.5%) as a pH adjuster/neutralizer for carbomer or acrylic thickeners in leave-on lotions, serums, and sunscreens, and in rinse-off cleansers. Higher-strength consumer products (e.g., certain hair-removal/depilatory creams, strong soap-free cleansing creams, and some high-alkaline cream systems) can use TEA in the ~1–5% range to neutralize fatty acids or polymers and build structure; above this is uncommon in OTC cosmetics due to irritation potential and nitrosamine-control considerations under EU/FDA good manufacturing practice.