What is the best serum or cream for the dark circle under eye and what is the important ingredients that help to reduce or whitening the eye??

See Skin Dr: There are specialized creams for dark spots but should be prescribed under the supervision of a dermatologist. There are some topical steroids that can reduce blemishes and spots but the danger is that it could enter your eye and cause Glaucoma. The best advice is to wear sun block , wear a hat, avoiding the sun and see your skin doctor. Best wishes.

There is no "best": As that's why you'll see possibly >100 different creams that claim to improve under eye issues, as in darkness, puffiness, etc. Remember much of these issues are age and genetic related. You also want to make sure you avoid smoking, too much alcohol, sleep deprivation, too much stress, to much salt in your diet and sleeping stomach side down. But consider a cream with "retinol" in it.