Triethanolamine is a pH adjuster. It is a toxic component that can be absorbed by the skin and detected in blood later. It can be a dermal irritant. Though it's considered safe, you should think before using it in skincare. There are many products on the market without Triethanolamine.
Safety
Triethanolamine can be a dermal irritant, but it has not been shown to be a sensitizer. It is safe for use in cosmetic formulations designed for discontinuous, brief use followed by thorough rinsing from the surface of the skin; in products intended for prolonged contact with the skin, the concentration of DEA should not exceed 5%; should not be used with products containing N-nitrosating agents.