I was facing most unwanted dark circles for more than a year and posting question for effective remedy like a paranoid every where. You won't believe that I tried everything from Drugstore $5 to £11 pound product. None of their effect last longer. All I found if you are below 25 then collagen patches/ gel will work. But if you are already 30 or near to these regular products won't work on you as smoothly as they work on young skin.
I had a special problem of having dark circle on lid, Not under eye. Which actually happens for lack of iron in your body. I started to take Iron pills. Since my eating habit of vegetables were irregular since I am a full time worker and a mother.
The result:
After a month taking one pill everyday after breakfast my eye lids started to lighten up!! And after 2 months it became a bit more better. When I started I really had bad dark circles that's why I had to use orange color corrector every time underneath my concealer. After 3 months now I don't need any corrector and very little concealer. Neither my eyeshadow changes it color on my lid automatically which makes me happy like anything because I am gifted with naturally good quality skin.
Cons :
If your body is not having enough fiber in food diet, you may face constipation.
Good luck and say good bye to dark circle >3