one of the best treatment for dark spots is...prescription hydroquinone! I recommend combining it with a retinol and chemical exfoliant. You should use it in a 3 month cycle (3 months on, 3 months off) with other brightening agents like kojic acid, cysteamine, alpha arbutin, tranexamic acid, hexylresorcinol, licorice root, ellagic acid, mulberry & niacinamide What are your favorite products & ingredients for dark spots?