Olea europaea (Olive) oil is a triglyceride-rich lipid phase composed predominantly of oleic acid (C18:1, typically from 55 to 83%), with meaningful fractions of linoleic and palmitic acids, and a small but biologically relevant unsaponifiable portion containing squalene, phytosterols, and tocopherols. In skin care emulsions and anhydrous oils, olive oil functions as an emollient/occlusive, reducing perceived roughness and water loss while delivering slip and cushion. The unsaponifiable fraction — especially squalene — contributes antioxidative support and sensorial refinement; however, like all highly unsaturated oils, olive oil is oxidation-prone and benefits from co-formulation with antioxidants and oxygen/light-control packaging to maintain odor/color and preserve performance across shelf life.

In hair/scalp systems, olive oil provides fiber lubrication that decreases friction and improves wet/dry combability, particularly in damaged or textured hair. It integrates readily into conditioners, masks, and pre-shampoo treatments, where it augments the lamellar network formed by fatty alcohols and cationic polymers and helps reduce static/flyaways. Evidence reviews of plant oils underscore olive oil’s emollient and antioxidant attributes; nonetheless, use-context matters. Small controlled studies in adults/infants suggest pure olive oil can weaken stratum corneum integrity in susceptible skin. In cosmetic products, it is best positioned within balanced emulsions and not as continuous, repetitive monotherapy on very delicate or atopic skin.