Some people will say cucumbers are effective for dark circles, but others may think not. As far as I am concered, cucumbers can help get rid of dark circles. Dark circles are often caused by dry skin under your eyes. While a cucmber is rich in water containing 90% of water, so they can keep your skin under your eyes smooth. Once your dark circles get enough water, they will go away themselves. I've tried applying cucumbers to treat my dark circles and I found them helpful. However, dark circles can be caused by other factors, so you should figure out what cause your dark circles and treat your dark circles accordingly.