The most common lightening treatments are retinoids, vitamin C and vitamin E. The Retinol-Alpha-Tocopherol Complex, or RAC, is the most commonly used retinoid for lightening and darkening of skin. It's used for skin repair and for retinoid therapy. It's also used to treat acne, hyperpigmentation, and skin discoloration. RAC contains retinol and alpha-tocopherol, which has anti-inflammatory and antioxidant properties. The most popular retinoid is Retin-A, which is sold under the name Vitamin C. Retinoids work by preventing cells from dividing and the growth of new skin. There is some evidence that vitamin C may decrease the skin's sensitivity to sun damage. Retinoids are also used for the treatment of acne and hyperpigmentation. It is also used to treat psoriasis, eczema, and scarring.
There are other retinoids, but none have been tested in humans to date. If you don't know your product is retinoid-based, it is hard to know if it really does the job for you. For the record, I have never purchased any retinoid products and my dermatologist has not tested them for me. My dermatologist's name is Dr. K. She is a board-certified dermatologist and is the head of the Department of Dermatology at Boston Medical Center. I have not taken retinoids for my skin in 10 years and have never had a dermatologic problem.