Shadows under your eyes can be the result of several factors: allergies, irritation, dehydration, fatigue, nasal congestion, sun exposure or thinning skin. The skin under the eyes is already thin to begin with (about half a millimeter thick) so the veins below the surface can show through and create a blue cast. If you have deep set eyes or very fair skin, the effect is even more pronounced. if you have a dark skin tone, the pigment can also collect under your eyes to create circles.
To address pigmentation issues, look for an eye cream containing licorice and hyaluronic acid. Studies show that these ingredients reduce dark circles after six weeks of use. Retinols may help those with thinning skin.
For quick home remedy, soak cotton balls in cold soy milk. The coolness and the anti-inflammatory properties of soy can help reduce irritation and puffiness. Also, try adding a pillow at night. Elevating your head during sleep can help prevent fluids from collecting under your eyes.
You can also cover up the problem with concealer. Look for a product thats a shade lighter than your foundation and with a creamy thicker consistency. Apply the concealer in light, featherly strokes using a makeup sponge or a flat makeup brush.