AbstractObjectiveThe moisturizing and irritation effects of sacha inchi oil were evaluated.Study Design The moisturizing effect on the skin was clinically assessed using a regression study design. Sacha inchi oil or olive oil (benchmark) was applied on the left or right lower leg of the subjects for 14 days followed by application discontinuation for 2 days. The TEWL, skin moisture content and dryness appearance were observed.MethodsThe fatty acid composition and characteristics of cold‐pressed sacha inchi seed oil were determined. Skin tissues cultured ex vivo were used to assess primary irritation induced by the oil by examining keratin 1 expression and TNF‐α and IL‐1α release from the oil‐applied tissues.ResultsThe sacha inchi oil contained 42.3% linolenic acid and 39.5% linoleic acid. This oil's saponification, iodine, acid and peroxide values were 168.58 ± 1.55 mg KOH/g, 203.00 ± 0.04 g I2/100 g, 1.68 ± 0.03 mg KOH/g, and 1.95 ± 0.26 mEq peroxide/kg, respectively. Compared with nontreated skin tissues, induced secretion of TNF‐α and IL‐1α and disruption of keratin 1 integrity in the stratum corneum layer were not found in the sacha inchi oil‐treated tissues. In a clinical study with 13 volunteers, the improvement in moisture content and skin dryness appearance at the sacha inchi oil‐applied site was comparable with that observed at the olive oil‐applied site.ConclusionsThe sacha inchi oil was mild to the skin and benefited dry skin.