Gradually diminishes dark spots with 4% hydroquinone, and provides Vitamins C and Vitamin E to your skin while you sleep. Prescription required. Contact your healthcare provider to purchase, or find a nearby physician who offers this product. With Obagi-C Rx, you're on your way to healthier, refreshed, revitalized skin from cell to surface. Obagi-C Rx Systems promote skin rejuvenation from the inside out using a formulation of prescription-strength hydroquinone USP, 4%, which reduces the appearance of hyperpigmentation and age spots, combined with 10% L-Ascorbic Acid (Vitamin C)—the only topical antioxidant proven to stimulate collagen synthesis and protect your skin by minimizing future skin cell damage.
INGREDIENTS 
HYDROQUINONE 4%
Strong inhibitor of melanin production that has long been established as the most effective ingredient for reducing and potentially eliminating melasma.
FULL INGREDIENTS
water (aqua), glycerin, cetyl alcohol, PPG-2 myristyl ether propianate, sodium lauryl sulfate, TEA-salicylate, latic acid, phenyl trimethicone, tocopheryl acetate, sodium metabisulfite, ascorbic acid, methylparben, disodium EDTA, propylparaben, saponins, BHT
SAFETY I FORMATION 
Obagi-C Rx C-Clarifying Serum (Normal to Oily & Normal to Dry) and C-Therapy Night Cream contains 4% hydroquinone
CONTRAINDICATIONS: People with prior history of sensitivity or allergic reaction to this product or any of its ingredients should not use it. The safety of topical hydroquinone use during pregnancy or in children (12 years and under) has not been established.