At its definition, dehydration means that your body is losing more water than it’s taking in. Aside from not drinking enough water, this can be related to increased urination from caffeine or diuretics. It may also occur from lots of sweating from exercise.
Unlike dry skin, dehydration can cause the following symptoms:
darker under-eye circles
“shadows” around the face (especially under the eyes and around your nose)
increased incidence or appearance of fine lines and surface wrinkles