Non-sensitizing plant extract (also known by its Latin name of Cucumis sativus). Most types of cucumber are composed of 95% water, and the other constituents primarily include ascorbic acid (vitamin C), caffeic acid (an antioxidant), fatty acids, the mineral silica, plus other trace minerals. Due to its antioxidant activity, cucumber is a welcome addition to anti-aging products.
Cucumber contains fragrant components that are not sensitizing to skin (a rarity) so it can be used to enhance the natural scent of a cosmetic product without issue.
While this ingredient is often reported to be useful for improving the appearance of puffy eyes there is not adequate, reliable research to support this contention.
In case you’re wondering: The act of placing slightly chilled cucumber slices over the eye may help reduce puffiness, but that’s not because the cucumber has de-puffing properties. Rather, it’s the coolness of it that diminishes puffiness and constricts the skin, and cucumber slices just happen to fit the contours of the eye area.
References for this information:
International Journal of Toxicology, May 2014, pages 47-67
Archives of Dermatological Research, May 2011, pages 247-252
Natural Product Research, October 2010, pages 1537-1545