Medically speaking, the Mayo Clinic defines dark eye circles as "round, uniform areas of pigmentation beneath each eye." Under-eye circles can make you appear haggard and exhausted, although late nights and lack of sleep are rarely the main cause. Getting rid of dark eye circles means first pinpointing the exact cause.
If you have airborne allergies, this may cause blood to collect in the blood vessels under your eyes. As the blood vessels dilate, this can worsen the appearance of dark under-eye circles, says Yale University School of Medicine's John A. Persing, M.D. In addition to dark circles, the eyes might also appear puffy. The solution may be found in an over-the-counter antihistamine, but first get your doctor's opinion.
If other family members have dark circles under the eyes, you might have them as well. Diane Berson, M.D., a dermatologist at Weill Medical College of Cornell University, states that dark circles under the eyes are "a combination of heredity and genetics."
Too much pigmentation in the skin under the eyes causes dark eye circles. The New York Times states that people with all skin tones can have dark circles, but they're more problematic in those of African-American, southeast Asian and southern Italian descent. Exposure to the sun can make the problem worse, cautions the Mayo Clinic, as it encourages more melanin (pigment) production. Apply a lightweight, non-greasy moisturizer under the eyes that includes sunscreen protection.
Common to the aging process is collagen depletion and reduced fat, making the skin under the eyes thinner. This makes the blood vessels under your eyes appear more pronounced. The Mayo Clinic also adds that puffy eyelids caused by aging can cast shadows under your eyes, making it appear as though you have dark eye circles.
Drinking too much alcohol and caffeine results in dehydration, which causes thinner skin. The Mayo Clinic also states that smoking can make eye circles worse. Begoun recommends applying an emollient moisturizer under the eyes to reduce dry, flaky skin.