of your skin is genetically determined.So, if you are a light skinned individual then the use of any products to further lighten may not be that effective.
The skin lightening agents that are available are all meant to reduce areas of hyper-pigmentation, to bring it to an even skin tone.
Skin whitening is a term covering a variety of cosmetic methods used to whiten the skin.
Many treatments use a combination of topical lotions or gels containing melanin-inhibiting ingredients along with a sunscreen, and a prescription retinoid. Depending on how the skin responds to these treatments, exfoliants — either in the form of topical cosmetic or chemical peels — and lasers may be used.
Topical hydroquinone is considered by many dermatologists to be a safer, similarly effective (if not more so), and less expensive option than lasers or deep peel treatments. Topical hydroquinone comes in 2% (available in cosmetics) to 4% (or more) concentrations (available from a physician or by prescription), alone or in combination with tretinoin 0.05% to 0.1%.
Some research has shown topical azelaic acid in 15% to 20% concentrations to be as efficacious as hydroquinone with a decreased risk of irritation. Tretinoin by itself has also been shown to be useful in treating hyperpigmentation
-damaged skin. Kojic acid, alone or in combination with glycolic acid or hydroquinone, also has shown good results.
ref:http://en.wikipedia.org/wiki/Skin_whitening