Obagi C Rx System effectively repairs photodamaged skin with a potent combination of L-ascorbic acid (vitamin C) and 4% hydroquinone. This prescription-strength blend works to exfoliate and renew the skin for a brighter, more even complexion. Obagi C Rx System helps to prevent future skin damage by boosting skin's natural defenses with the antioxidant power of vitamin C. Obagi C Rx System reverses the signs of aging by stimulating collagen production in the skin.