How can I get lighten dark skin on the back of my thighs?

Bleaching agents. Topical bleaching creams such as hydroquinone, azelaic acid, kojic acid, and newer bleaching agents such as elure can help lighten hyperpigmented or darker areas. Combining a bleaching agent with an exfoliant such as glycolic acid or tretinoin can help to enhance the effects of the bleaching agent by allowing for deeper penetration into the skin. Important to avoid sun damage or exposure.