Epiestriol (INN) (brand names Actriol, Arcagynil, Klimadoral), or epioestriol (BAN), also known as 16β-epiestriol or simply 16-epiestriol as well as 16β-hydroxy-17β-estradiol, is an endogenous, steroidal, weak estrogen, and the 16-epimer of estriol (which is 16α-hydroxy-17β-estradiol). Epiestriol is (or has previously been) used clinically in the treatment of acne. In addition to its estrogenic actions, epiestriol has been found to possess significant anti-inflammatory properties without glycogenic activity or immunosuppressive effects, an interesting finding that is in contrast to conventional anti-inflammatory steroids like hydrocortisone (aglucocorticoid).