Tetrahexyldecyl ascorbate, aka THD, is a gentler, oil-soluble version of vitamin C. Most commonly, vitamin C comes in the form of L-ascorbic acid, which can irritate the skin and is actually less shelf stable than THD.

THD, when stabilized by acetyl zingerone (which we also use in our products that contain THD), offers all the benefits you can expect from a vitamin C.

THD's brightening capabilities can improve the appearance of dark spots, post-inflammatory hyperpigmentation, and uneven skin tone.

THD also increases collagen production in your skin, improving the skin's firmness while smoothing the appearance of fine lines and wrinkles. THD's antioxidant-rich makeup also protects skin from the free radical damage and oxidative stress that ages it.

THD, unlike L-ascorbic acid, is oil-soluble, meaning you'll find this form of vitamin C in oil-based serums.