There is a home remedy that my mother is doing. She put a table spoon of baking soda, with shredded potato (raw) , mixed it thoroughly and she put it on her face, elbows, knees and armpit. It lightens the dark color. She was doing this for a month and she do it 3 times a week, and now that dark spot is vanishing already, especially on her face and elbow. She have freckles, and it really lightens the brown spot on her. Before she only hide it with foundation or BB cream. It works. But now, she can only use a powder and it is all gone. She keeps on doing it because it really works. Even on her under am, it is lightens already. The only disadvantage is you need to use a moisturizer to your face, and gentle lotion to your elbow and knees because it is easy to get dry. Baking soda can dry your skin.