Dark circles have several causes, and what helps depends on which applies to you.
Common causes
Reference health sources list nasal congestion from colds or allergies, lack of sleep, eczema or rubbing itchy eyes, dehydration, family traits and uneven pigmentation. Rarely, bruising can be the cause.
What can help
Rest, treating allergies or eczema, and drinking enough fluids can help where those are the cause. Sun protection around the eyes is also sensible, and cosmetic concealer can mask colour. Dark circles caused by family traits or pigmentation usually need no treatment.
When to get checked
See a doctor if you think the area may be bruised, if allergy symptoms do not improve, or if the changes appear suddenly or affect only one eye.
Source: SickKids: Dark circles under the eyes. This is general information, not medical advice.
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